What I find very frustrating when it comes to RAW video recording on 50D is the lack of information from ML developers about the most basic things - where to start, how does it work, which camera settings to use. I am good in photography, but novice in DSLR video, and I've been struggling for some time to get some answers here. It is probably here, spread in small bits across 109 pages of this massive thread, which makes it essentially unusable.
Anyway, I did some googling, and here is the number one place to visit if you are new to 50D RAW video:
http://www.eoshd.com/content/10770/canon-50d-magic-lantern-raw-reviewThis is a great review, aimed at novices like myself. For the first time I figured out what are differences, advantages and drawbacks for the full sensor and crop video recording. Now I know that the actual full sensor video resolution of 50D is 1584 x 1058 pixels, and it has some serious artifacts because of the way Canon does it. From reading other web resources I know now that how exactly DLR sensor is used for 1080p video recording is is not known - it is a "black box", fully hidden inside Canon firmware, or perhaps even done on hardware level. People can only speculate, based on actual video resolution measured from video, and amount of aliasing and moire artifacts. It looks like the best possible approach - binning sensor pixels into super-pixels for video - is not possible because of the limited bandwidth from the sensor. People speculate that some combination of binning and line skipping takes place, to reduce the bandwidth. This is really bad from a photographer's perspective - with huge DSLR sensors you'd expect to gain a lot in terms of light sensitivity (compared to consumer camcorders), but if you only do skipping, you don't gain anything - DSLR pixels are probably as small (or even smaller) than camcorder pixels.
People seem to be obsessed with crop video shooting, with the idea that the image quality should be much better, but as a photographer I can tell you that even the most expensive lenses (like my 135L) don't shine when viewed as 100% crops, especially wide open (and that's how I always use them - for DoF control). In other words, image quality is not great in crop video mode because of the lens limitations. One has to stop lenses down a lot to beat that. The second big negative coming from the crop mode is that you give up on DoF control (if you ask me, the main reason one should do DSLR video, and not consumer camcorder video) - because of the stopping down, and because of the fact that you are effectively working with a tiny size sensor (probably same size as camcorder sensor).
I wish this info, and more (like, details on shutter, aperture and ISO control when shooting raw video) where available somewhere as a single post, for novices. Then your great product would be appreciated even more.