We rendered out several videos from After Effects using the MPEG-4 preset. The resulting files do not play in Quicktime (Mountain Lion) or other QT-based apps like iTunes; they only play properly in apps like VLC, MPlayer, Streamclip, etc. They also play fine in Quicktime on a PC.
What is it with these mp4s that makes them incompatible with Quicktime? Or is this a Quicktime bug?
JVK