I am having some issues with some H264 encoded video files and their audio being out of sync. On the website, the files can be played either through a flash-based player (FlowPlayer) or the QuickTime player. The problem never occurs in the QT player, only in FlowPlayer, and it doesn't occur with all of the videos, only some. All of the videos were ripped using Handbrake on a MacBook Pro.

I am wondering if anyone knows why this may be occuring, and what can be done to fix the issue?

Thanks in advance