Troubleshooting
Startup problems
In case of startup problems it often helps to delete the plist in home/library/preferences.
Most problems are caused by failed projects that the application tries to resume. Use the Resume Projects dialog to cancel one or all of the unfinishhed projects. Alternatively you can delete individual projects from the plist using Property List Editor which is part of the XCode Tools installation (use Pacifist to extract it from the package on the installer DVDs).
Sometimes the log gets corrupt. Try deleting it in home/library/logs.
If an export hangs or crashes you may need to force quit one or more JES Movie Export Servers using the Activity Monitor.
Spotlight
Spotlight indexing can slow-down the saving of a large movie. To prevent indexing, go to System Preferences/Spotlight/Privacy and add the folder you save movies to to the set of "private" folders and disks.
MPEG
QuickTime cannot play the sound of "muxed" MPEG files (containing both video and sound). For demuxing MPEG Streamclip is advised. QuickTime 7.6 can play and extract MP2 sound (very slowly).
To open the video of an MPEG2 file you need the QuickTime MPEG2 playback component which can be bought at the Apple Store. For mp2 sound you need at least v7.6. If a sound file of the same name is present in the same folder it is opened too.
QuickTime provides no MPEG2 export. Only Pro apps and iDVD can do this using proprietary software.
Multiprocessing
Sometimes a project on a multicore machine isn't as fast as you may expect. Use the Activity Monitor to check how much CPU is used.
Disk I/O may be the limiting factor, especially if you read or write over a network. For top I/O speed read from one local disk and write to another.
Some Deinterlacer features aren't multiprocessing yet. The following are MP: deinterlace, modify color, scale (part of standards conversion), compress.
If you are a power user you can use Shark to find the slowest part of the pipeline. If you find a bottleneck report it to me.
Copy-protected media
Protected video cannot be converted.
Protected audio can only be copied, not exported or recompressed (even if you authenticate).
If you export to a QuickTime Movie file you can copy the sound manually afterwards, using QT Player Pro.
If you want sound to play during the conversion you need to authenticate (if your computer hasn't been authenticated yet).