There's a couple videos that the account setting doesn't apply to.
Ruger, I'll admit, a lot of videos really are crap quality, on some of them it's a hug difference.
Not the greatest example, but you can see and hear the difference:
Code:
watch?v=r3zrJyNgyNQ
versus
Code:
watch?v=r3zrJyNgyNQ&fmt=18
(remove the space)
Note that youtube doesn't have the option to watch a bettter quality version if you use the normal link.