I tried searching for this issue, because I know I saw it when I was looking for other stuff, but can't remember what forum I saw it on!
I just got the Retail Mavericks running on my AMD setup and I thought all was well until I tried to play .avi movies.
The sound/audio isn't in sync with the video. Tried using Quicktime and VLC player, same thing.
Movie files play perfectly fine on my Windows 7 hdd.
However, watching videos on Youtube seem totally fine.
Thanks for any and all help!