QuickTime is the default movie player in Mac OS X. Because of it's ability to play a wide range of video and audio media, QuickTime Player is a convenient tool for most users. Being able to show the last file played using QuickTime Player can help an investigator show intent.
You can use the MacForensicsLab analyze function to explore the following file: ~/Library/Preferences/com.apple.quicktimeplayer.plist This file shows recently viewed movies and audio clips (any files opened in the program QuickTime Player.app). This file also shows "NSNavLastRootDirectory" the default directory (last accessed) that was used for opening each movie. The pathnames and document name inside this file could be useful for your forensic investigation.