Apple Final Cut Pro 7 - Manual (Page 605)

Synchronizing Dual System Recorded Video and Audio
If you are working with captured audio and video from different sources (dual system
recording), you’ll probably want to link the audio and video clips by merging them into
single clips in the Browser after syncing them. This way you can easily work with them
as single clips in the Timeline or the Browser, as if you had captured each one as a single
clip and media file. Before actually merging two or more clip items, you first need to find
a synchronization point between them. There are different ways of doing this, depending
on how you shot your footage. See
“Merging Clips from Dual System Video and Audio”
for details.
605 Chapter 40 Linking and Editing Video and Audio in Sync