You've probably all seen this, but anyway here's some High Definition Gameplay Footage from Diablo 3, Announcements, and trailers.
[HD] Cinematic Trailer
Cinematic Trailer - Voodoo Extreme
2008 WWI - Diablo 3 Announcement
2008 WWI - Diablo 3 Announcement on Vimeo
[HD] Diablo III (3) GamePlay
Twenty-Minute Gameplay Movie - Voodoo Extreme (HUGE video, fast internet recommended )
Diablo III (3) GamePlay Trailer
All streaming links. Enjoy.