QuickTime Player 7 can be very useful for quickly trimming a clip or outputting different sections of a movie to separate files. This can be accomplished by setting the in and out points, going to Edit > Trim to Selection and then exporting the file or doing a Save As.
However, if you accidentally hit Save instead of Save As and then close the movie (this happens more often than you'd think), the movie will be permanently trimmed.
Luckily QT Repair in Pro Maintenance Tools can fix this. The repair assumes that the trimmed data still exists in the file and that the movie is capable of being opened in QuickTime Player and played back, albeit at a shorter length.
1. First of all, check that the trimmed data is still in the file. Open the file in QuickTime Player and press Cmd+I to view the Info window. Compare the Data Size section to the size listed by the Finder - if the size on disk is significantly larger, that means the data is still within the file.
2. Launch QT Repair and open the movie clip.
3. In the Quick Start dialog, choose the option to restore trimmed edits.
Once the backup is complete, processing should be very quick.