@Danne: Look this: slightly more blurred and correct color:
ffmpeg -i M05-0608.mov -filter_complex "[0:v] boxblur=1 [tmp]; [0:v][tmp] blend=all_mode='normal':all_opacity=0.5" -f matroska - | \
ffmpeg -i - -vf minterpolate=50,tblend=all_mode=average,framestep=2 -f matroska - | \
ffmpeg -i - -vf minterpolate=50,tblend=all_mode=average,framestep=2 -f matroska - | \
ffmpeg -i - -c:a copy -c:v prores_ks -profile:v 2 -pix_fmt yuv422p10 -color_primaries bt709 -color_trc bt709 -colorspace bt709 -vf minterpolate=50,tblend=all_mode=average,framestep=2,unsharp=7:7:0.8:7:7:0 out.mov
The higher the opactiy value, the sharper the result.
Edit: it is commited to the MLVApp repos, so you can try it out. To play with the values, look at line 1472 in MainWindow.cpp. I think we have to raise opacity in order to get a sharper image.