[SomeRandomUser]

Failing to load HD versions of the video and then graying them out (reloading the page usually makes it work again), play the video in 320p and display the resolution as set to HD, SD to HD loading ad infinitum (or just display an error and stop playback), stop buffering after skipping (even to pre-buffered parts), really low streaming speeds (that fix after reloading the page), etc, etc.

Making a general video host is so expensive and complicated that we may have to just resign to use YouTube for at least some more years... but it's easily one of the worst user experiences regarding online videos.

[PavlovsCat]

For longer stuff, and when I know I will likely skip back and forth, I use a browser extension to download the video as mp4, and then VLC to watch it while it's still downloading.. so much nicer.