"YouTube works" is ambiguous because YouTube is two distinct things: video playback and the actual website UI. E.g. YouTube video plays Ok on Raspberry Pi (I believe this can be attributed to hardware codecs) but the rest of the elements of a YouTube page work painfully slow and YouTube is not alone in this, there are other websites (including ones lacking any multimedia content) which work really slow as well. I haven't seen any which would be completely unusable though, it's just really annoying to use some.
