Apple Final Cut Express HD - Manual (Page 407)

Chapter 29 Linking and Editing Video and Audio in Sync 407
VI
If the item is an anchor item (either the sole video item among linked items, or the
topmost audio item if there is no video item), it moves into sync with the topmost
out-of-sync audio item in the group, starting on track A1 and going down. Otherwise,
the selected item moves into sync with the anchor item to which it’s linked.
Before syncing
Control-click the out-of-sync
indicator and choose Move
into Sync.
After syncing
The anchor item is moved into
sync with the topmost audio
item to which it’s linked.