So YouTube has three different qualities that I see quite often: Normal Quality, High Quality and High Definition (HD). Every video seems to be available in Normal Quality. Also, High Quality appears to generally be the same size as Normal and those can ben standard format (TV shaped) or wide screen formatted. But I think recently (towards the end of 2008?) the normal became wider to suit more widescreen video, as a result you get black bars on the sides for standard video instead of the tops and bottoms for the widescreen.
But the High Def video shows up as standard size video but the HD video shows up huge on the screen (about 864×480). I remember it being large before, but not that large, maybe it takes longer to convert or they approve it or something or did I just never notice before?
For example, this is the same fire dancing video I posted before and I don’t ever remember it being so big on the screen let alone so clear. Be sure to toggle between “Watch in Normal Quality” and “Watch in HD” to see the difference.