I've been working with fairly large files (200MB original files, 45MB SWF files) and have not noticed the player slowing down the video. I have, however, noticed that larger video (320x240) seems to drift after a couple of minutes, so that by the end the audio is out of sync with the video by like 1 second. I noticed someone has processed a 15 minute video, did you have any problem with audio drifting?