2.5mbps are youtube's own recommendations: https://support.google.com/youtube/answer/1722171?hl=en#zippy=%2Cbitrate https://support.google.com/youtube/answer/17

2.5mbps are youtube's own recommendations: https://support.google.com/youtube/answer/1722171?hl=en#zippy=%2Cbitrate https://support.google.com/youtube/answer/1722171?hl=en#zipp... They will then transcode it to h265, or webm which uses even less bandwidth, but I'm giving them the benefit of the doubt here and assuming they target their transcoding setup to preserve as much quality as they recommend providing them. And of course this is VBR not CBR, so some scenes will use less. 4mbps is the linked article description of where h264 matches DVD quality. Yes, 4mbps is more than most streaming sites will give for 480p. This does mean that most streaming sites are inferior to DVDs at 480p. The fact that most streaming sites use less bitrate than a DVD-equivalent quality is therefore not surprising, giving that people have noticed that exact fact. Streaming sites do not pick their bitrate to maximise quality given a fixed maximum filesize, so it's not surprising that they choose a lower bitrate (and therefore lower quality) than DVDs. They're instead optimizing for things like their server costs, time to playback start, or the ability to perform uninterrupted playback over the internet connection of users resorting to these lower resolution settings.