Okaaay. Two binaries? I never tried to unpack the image. I just have compiled it and I was happy when the appimage process ended without error but with an appimage. 
Here is the directory/file tree of the unpacked AppImage:
squashfs-root
├── AppRun -> usr/bin/mlvapp
├── Makefile
├── mlvapp
├── mlvapp.desktop
├── MLVAPP.png
├── raw2mlv
└── usr
├── bin
│ ├── ffmpeg
│ ├── mlvapp
│ ├── qt.conf
│ └── raw2mlv
├── lib
│ ├── libasyncns.so.0
│ ├── libdbus-1.so.3
│ ├── libEGL.so.1
│ ├── libffi.so.6
│ ├── libFLAC.so.8
│ ├── libgbm.so.1
│ ├── libgmodule-2.0.so.0
│ ├── libgomp.so.1
│ ├── libgstapp-1.0.so.0
│ ├── libgstaudio-1.0.so.0
│ ├── libgstbase-1.0.so.0
│ ├── libgstpbutils-1.0.so.0
│ ├── libgstreamer-1.0.so.0
│ ├── libgsttag-1.0.so.0
│ ├── libgstvideo-1.0.so.0
│ ├── libgthread-2.0.so.0
│ ├── libicudata.so.56
│ ├── libicui18n.so.56
│ ├── libicuuc.so.56
│ ├── libjasper.so.1
│ ├── libjpeg.so.8
│ ├── libjson-c.so.2
│ ├── libogg.so.0
│ ├── liborc-0.4.so.0
│ ├── libpcre.so.3
│ ├── libpng12.so.0
│ ├── libpulsecommon-4.0.so
│ ├── libpulse-mainloop-glib.so.0
│ ├── libpulse.so.0
│ ├── libqgsttools_p.so.1
│ ├── libQt5Core.so.5
│ ├── libQt5DBus.so.5
│ ├── libQt5Gui.so.5
│ ├── libQt5Multimedia.so.5
│ ├── libQt5MultimediaWidgets.so.5
│ ├── libQt5Network.so.5
│ ├── libQt5OpenGL.so.5
│ ├── libQt5Widgets.so.5
│ ├── libQt5XcbQpa.so.5
│ ├── libsndfile.so.1
│ ├── libvorbisenc.so.2
│ ├── libvorbis.so.0
│ ├── libwayland-client.so.0
│ ├── libwayland-server.so.0
│ ├── libwrap.so.0
│ ├── libX11-xcb.so.1
│ ├── libXau.so.6
│ ├── libxcb-dri2.so.0
│ ├── libxcb-dri3.so.0
│ ├── libxcb-glx.so.0
│ ├── libxcb-present.so.0
│ ├── libxcb-sync.so.1
│ ├── libxcb-xfixes.so.0
│ ├── libXdamage.so.1
│ ├── libXdmcp.so.6
│ ├── libXext.so.6
│ ├── libXfixes.so.3
│ ├── libXi.so.6
│ ├── libxshmfence.so.1
│ └── libXxf86vm.so.1
├── plugins
│ ├── audio
│ │ ├── libqtaudio_alsa.so
│ │ └── libqtmedia_pulse.so
│ ├── bearer
│ │ ├── libqconnmanbearer.so
│ │ ├── libqgenericbearer.so
│ │ └── libqnmbearer.so
│ ├── imageformats
│ │ ├── libqgif.so
│ │ ├── libqicns.so
│ │ ├── libqico.so
│ │ ├── libqjp2.so
│ │ ├── libqjpeg.so
│ │ ├── libqtga.so
│ │ ├── libqtiff.so
│ │ ├── libqwbmp.so
│ │ └── libqwebp.so
│ ├── mediaservice
│ │ ├── libgstaudiodecoder.so
│ │ ├── libgstcamerabin.so
│ │ ├── libgstmediacapture.so
│ │ └── libgstmediaplayer.so
│ ├── platforminputcontexts
│ │ ├── libcomposeplatforminputcontextplugin.so
│ │ └── libibusplatforminputcontextplugin.so
│ ├── platforms
│ │ └── libqxcb.so
│ └── xcbglintegrations
│ ├── libqxcb-egl-integration.so
│ └── libqxcb-glx-integration.so
├── share
│ ├── applications
│ │ └── mlvapp.desktop
│ ├── doc
│ │ ├── libasyncns0
│ │ │ └── copyright
│ │ ├── libdbus-1-3
│ │ │ └── copyright
│ │ ├── libegl1-mesa-lts-xenial
│ │ │ └── copyright
│ │ ├── libffi6
│ │ │ └── copyright
│ │ ├── libflac8
│ │ │ └── copyright
│ │ ├── libglib2.0-0
│ │ │ └── copyright
│ │ ├── libgstreamer1.0-0
│ │ │ └── copyright
│ │ ├── libgstreamer-plugins-base1.0-0
│ │ │ └── copyright
│ │ ├── libjasper1
│ │ │ └── copyright
│ │ ├── libjpeg-turbo8
│ │ │ └── copyright
│ │ ├── libjson-c2
│ │ │ └── copyright
│ │ ├── libogg0
│ │ │ └── copyright
│ │ ├── liborc-0.4-0
│ │ │ └── copyright
│ │ ├── libpcre3
│ │ │ └── copyright
│ │ ├── libpng12-0
│ │ │ └── copyright
│ │ ├── libpulse0
│ │ │ └── copyright
│ │ ├── libpulse-mainloop-glib0
│ │ │ └── copyright
│ │ ├── libsndfile1
│ │ │ └── copyright
│ │ ├── libvorbis0a
│ │ │ └── copyright
│ │ ├── libvorbisenc2
│ │ │ └── copyright
│ │ ├── libwayland-client0
│ │ │ └── copyright
│ │ ├── libwayland-server0
│ │ │ └── copyright
│ │ ├── libwrap0
│ │ │ └── copyright
│ │ ├── libx11-xcb1
│ │ │ └── copyright
│ │ ├── libxau6
│ │ │ └── copyright
│ │ ├── libxcb-dri2-0-dev
│ │ │ └── copyright
│ │ ├── libxcb-dri3-0
│ │ │ └── copyright
│ │ ├── libxcb-glx0-dev
│ │ │ └── copyright
│ │ ├── libxcb-present0
│ │ │ └── copyright
│ │ ├── libxcb-sync1
│ │ │ └── copyright
│ │ ├── libxcb-xfixes0
│ │ │ └── copyright
│ │ ├── libxdamage1
│ │ │ └── copyright
│ │ ├── libxdmcp6
│ │ │ └── copyright
│ │ ├── libxext6
│ │ │ └── copyright
│ │ ├── libxfixes3
│ │ │ └── copyright
│ │ ├── libxi6
│ │ │ └── copyright
│ │ ├── libxshmfence1
│ │ │ └── copyright
│ │ └── libxxf86vm1
│ │ └── copyright
│ └── icons
│ └── hicolor
│ └── 512x512
│ └── apps
│ └── MLVAPP.png
└── translations
├── qt_bg.qm
├── qt_ca.qm
├── qt_cs.qm
├── qt_da.qm
├── qt_de.qm
├── qt_en.qm
├── qt_es.qm
├── qt_fi.qm
├── qt_fr.qm
├── qt_gd.qm
├── qt_he.qm
├── qt_hu.qm
├── qt_it.qm
├── qt_ja.qm
├── qt_ko.qm
├── qt_lv.qm
├── qt_pl.qm
├── qt_ru.qm
├── qt_sk.qm
└── qt_uk.qm
57 directories, 153 filesAs you can see, there are two "mlvapp" binaries, along with the "AppRun" link to the working mlvapp binary).
Also note the two "raw2mlv" binaries plus the single instance of "ffmpeg."
In addition, there are two "MLVAPP.png" images.
The included ffmpeg version should be used always!!! If you use another ffmpeg, nobody knows if it works for all features. It is just important, that ffmpeg is in the same folder as the mlvapp executable. Otherwise it should not work. Same for raw2mlv. It must be located in the same folder!
The MLV-App Wiki instructs Linux users to copy their system's version of ffmpeg into MLV-Apps extracted root directory. This action is sort of futile, as the mlvapp binary in that root directory fails while seeking dependencies on the user's system (specifically, in "/usr/lib/").
However, if one runs the mlvapp binary found in the extracted "/squashfs-root/usr/bin/" directory, MLV-App and the included ffmpeg binary works. By the way, I tried replacing that included version of ffmpeg with the one on my system and I didn't have any trouble exporting an MP4 file from MLV-App.
The reason why we write to use the drag and drop feature is, it always works. In the past it felt like 90% of the users failed with manual copy actions. And for some people even the drag and drop is hard to understand. But if copying the files works for, you can always do that!
After more than 40 years of the personal computing era, the preponderance of computer illiteracy is staggering. It is amazing how many folks have trouble with something as fundamental as copying files from one directory to another.
Regardless, the instructions should mention the fact that the focus pixel maps are merely copied into a directory, and the instructions should also give the location and name of that directory ("/squashfs-root/usr/bin/" for the extracted Linux AppImage).
Feel free to contribute! That is very much welcome! Also if you find a way to create the appimage in a better way, you can help if you like. We implemented MLVApp mostly on OSX. On Windows I know how to get it to work. But on Linux I am just happy if it compiles and creates the appimage somehow, and it starts if I doubleclick the image. 
Okay! Should I just DM the instructions to you?
In regards to creating an AppImage, my experience is limited mostly to running them and to the extraction that I had to perform to add the focus pixel maps. I cannot speak for every Linux user, but I would prefer the additional option of having the files and directories of the app packed into a standard tar archive (or a compressed tar archive). Although one can run an AppImage with only one command (or mouse click), the user must still unpack the MLV-App Appimage to use focus pixel maps. It takes the same effort to unpack a tar archive and then run (click on) the binary. Plus, there is no "compiling" a tar archive -- just create the archive (just like a zip file) and compress it, if you like.
I am happy to help in the creation of an MLV-App tar archive (and in cleaning-up the files/folders), but making a tar archive from folders and files is really "dumb-simple."
No idea what this plugin folder is and what it does. Should be something from the appimage. MLVApp has no plugin feature at the moment.
Judging from what's listed in the directory/file tree above, it appears that the "/squashfs-root/usr/plugins/" directory contains needed shared object libraries related to decoding/encoding audio and video formats.
If a version of the "Blue Banana" interface was an option in MLV-App, it could ease simple color grading (although it is very powerful in Cinelerra).
There is a way to import non-mlv, yes, but there is no way to import non-raw files. DNG, CR2, ... can be transcoded to MLV via raw2mlv, which is included in the package. Use "Transcode and Import" from the menu. You'll find the menu action only, if raw2mlv is on the right place (same folder as MLVApp executable). MLVApp imports the created MLV when transcoding is ready.
I thought I saw a way to import jpegs in the MLV-App menus. Even if one converted a video to a series of jpegs and there was an import function, image degradation would be a concern. If importing jpegs is not possible, it might be a little unwieldy to convert video files to a compatible raw format, and then transcode with raw2mlv.
Some of us shoot ML H264 with boosted bit rate and/or all-I settings. So, it would be great to be able to use MLV-App on those ML-generated files.
Thanks!
