Proč na to jdeš tak vědecky? Nejsem moc veliký fanda videa na webu ale jenom tak ze zvědavosti jsem zkusil stáhnout nejaké random a youtube-dl to dává i v 1080p. Tu je log třeba z toho něco vyzjistíš...
$ youtube-dl -v https://vimeo.com/216131664
[debug] System config: []
[debug] User config: ['--no-check-certificate']
[debug] Custom config: []
[debug] Command-line args: ['-v', 'https://vimeo.com/216131664']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2017.05.09
[debug] Python version 3.6.1 - Linux-4.10.13-1-ARCH-x86_64-with-arch
[debug] exe versions: ffmpeg 3.3, ffprobe 3.3
[debug] Proxy map: {'https': 'http://localhost:3128', 'http': 'http://localhost:3128', 'no': 'localhost,127.*,192.168.*', 'ftp': 'http://localhost:3128'}
[vimeo] 216131664: Downloading webpage
[vimeo] 216131664: Extracting information
[vimeo] 216131664: Downloading webpage
[vimeo] 216131664: Downloading JSON metadata
[vimeo] 216131664: Checking Original video URL
[vimeo] 216131664: Downloading akfire_interconnect m3u8 information
[vimeo] 216131664: Downloading fastly_skyfire m3u8 information
[vimeo] 216131664: Downloading akfire_interconnect_quic MPD information
[vimeo] 216131664: Downloading akfire_interconnect_quic MPD information
[vimeo] 216131664: Downloading fastly_skyfire MPD information
[vimeo] 216131664: Downloading fastly_skyfire MPD information
[debug] Invoking downloader on 'https://skyfire.vimeocdn.com/1494626668-0x43e96a0bff15ec5f965ed3b52bcb3f9732275890/216131664/sep/video/746977295,746977299,746977298,746977297/../'
[dashsegments] Total fragments: 98
[download] Destination: DOUBLE KING-216131664.fdash-fastly_skyfire_sep-video-746977299.mp4
[download] 100% of 217.93MiB in 11:22
[debug] Invoking downloader on 'https://skyfire.vimeocdn.com/1494626668-0x43e96a0bff15ec5f965ed3b52bcb3f9732275890/216131664/sep/video/746977295,746977299,746977298,746977297/../'
[dashsegments] Total fragments: 98
[download] Destination: DOUBLE KING-216131664.fdash-fastly_skyfire_sep-audio-746977299.m4a
[download] 100% of 17.91MiB in 01:27
[ffmpeg] Merging formats into "DOUBLE KING-216131664.mp4"
[debug] ffmpeg command line: ffmpeg -y -i 'file:DOUBLE KING-216131664.fdash-fastly_skyfire_sep-video-746977299.mp4' -i 'file:DOUBLE KING-216131664.fdash-fastly_skyfire_sep-audio-746977299.m4a' -c copy -map 0:v:0 -map 1:a:0 'file:DOUBLE KING-216131664.temp.mp4'
Deleting original file DOUBLE KING-216131664.fdash-fastly_skyfire_sep-video-746977299.mp4 (pass -k to keep)
Deleting original file DOUBLE KING-216131664.fdash-fastly_skyfire_sep-audio-746977299.m4a (pass -k to keep)
youtube-dl -F na tebe vysype všecky dostupné formáty. ffmpeg to potom slepí dohromady pokud je audio oddělený od videa. S pythonem to neumím takže o tom co se děje pod pokličkou ti moc neporadím. Provozovatelé videoserverů navíc vymýšlí neustále nové a nové opičárny jak uživatelům znepříjemnit stahování, takže i když konečně zjistíš jak na to, nebude ti to fungovat dýl jak měsíc nebo dva.