by Kilrah » Sat Jan 08, 2011 2:03 pm
If your video is .mp4, turn on the "Use QuickTime plugin" option and it should be fine. If it's not, then your video is probably too good quality, in which case you should convert it either to .mp4 or to a lower resolution.
In general .mp4s with QT option on will play fine up to 720p HD or more, but other formats are limited to standard definition.