I've developed a commercial MPEG4 container solution which uses ANNEX B H.264 compliant video. The encoded media plays back fine in every Mac OS and Windows based media player I've tried, except for Quicktime. Quicktime X under Snow Leopard is rediculously buggy. It stops animating playback after a random amount of time (1-3mins). Seeking back through the media and resuming playback is fine but beyond the specific point, animation completely stops but playback time continues to increase. Quicktime 7.6.7 under Windows plays back fine, as long as the file is under 1GB. VLC Media Player is the only player under Mac OS I've tried that plays back the media flawlessly. I've spent a lot of time looking around consumer forums and found no educated discussion on current MPEG4 compatibility with any Quicktime versions/platforms. I was wondering if there were any QTAPI devs out there that could share their H.264 experiences. Thanks a bunch!!