> no mp3 (my car accepts mp3 only) Both AAC and Opus fix some of MP3's inherent design problems (like imperfect handling of short sharp transients no matter ho

> no mp3 (my car accepts mp3 only) Both AAC and Opus fix some of MP3's inherent design problems (like imperfect handling of short sharp transients no matter how much bitrate you throw at it), so the only reason to continue using MP3 is for compatibility with old devices. Since downloads aren't an official part of Youtube's offering, they don't have to care about old offline-only hardware players only supporting MP3, either and anything that's modern enough to still support either a Youtube app or the website will also support either AAC or Opus. > the bit rate is not very high There's also a high bitrate available, but only for subscribers.