where can i watch yu gi oh 5d?

http://www.youtube.com/user/shriekv
He uploads the raw episodes on Wednesdays (the same day they air in Japan), but it usually takes him a while to get the subbed episodes up. All of his videos are HQ, though, at least the ones I've watched.

http://www.youtube.com/user/prismweapon
This guy uploads subbed episodes pretty quickly (usually the same day the episode airs in Japan or the day after).

anime-media.com has them.

truveo.com usually has anime on it

http://www.youtube.com