i've been having occasional issues where a 1440p youtube video will buffer for ten or so seconds, then resume normally. no clue why, my internet's more than fast enough.
but it reminded me of a time where my internet very much wasn't fast enough. we used to have ADSL, and we'd get maybe 1.5mbps if we were lucky. i could watch 360p youtube videos with no buffering, or 480p if i paused the video for a few minutes to get it to preload far enough (back when that was a thing). sometimes i'd treat myself and wait five minutes to watch a ninety second video in glorious 720p.
for whatever reason -- maybe the app only supported lower bitrate streams, maybe it had a better wifi chip than my phone or laptop -- i could watch 480p without buffering or preloading specifically on my PS vita. other devices couldn't do it.
so i ended up watching a lot of youtube on that beautiful 544p OLED display.