... "Comparison of YouTube media encoding options" of http://en.wikipedia.org/wiki/YouTube
To play DASH MP4 files in players other than VLC, repack the files using GPAC MP4BOX tool:
a. Create iTunes m4a: mp4box -add dash_audio.mp4#1 -new itunesfile.m4a
b. Create standard MP4 video: mp4box -add dash_video.mp4#1 -add dash_audio.mp4#1 -new standard.mp4