Just a damn second:
[j39m@SERN ~]$ youtube-dl -x "https://www.youtube.com/watch?v=Zh9lynUFikc" [snip] [ffmpeg] Destination: Platinum Disco FULL HQ (Nisemonogatari Opening 3) by Yuka Iguchi-Zh9lynUFikc.opus
The video in question was uploaded in late August of this year. I know WebM has been around for some time, but this is beyond sneaky. Compare audio extracted (without transcoding) from an older video with the result now; I see a concrete difference, not just extension-tweaking:
[j39m@SERN ~]$ file ~/Documents/other_music/platinum_disco_full.opus /home/kalvin/Documents/other_music/platinum_disco_full.opus: Ogg data
[j39m@SERN ~]$ file ~/Documents/other_music/disco.ogg /home/kalvin/Documents/other_music/disco.ogg: Ogg data, Vorbis audio, stereo, 44100 Hz, ~256000 bps, created by: Xiph.Org libVorbis I
The homepage for Opus doesn’t give me much to go on. I had no idea it was already “production-ready,” whatever that means.
What are you playing at, YouTube? What are you doing that we don’t understand…?