Sync and Video : Working with Video in Pro Tools : Locking Video Tracks

Locking Video Tracks
You can lock one or more video tracks to prevent any video clips on those tracks from being edited.
When a video track is locked, Pro Tools restricts all editing operations involving the track (except for locking and unlocking video clips).
A locked video track displays a small lock to indicate that the video track has been locked and cannot be edited. (The lock does not appear if the Track Height of the video track is set to Mini.)
To lock a video track:
1 Select the video track or tracks you want to lock.
2 Do one of the following:
*   
Start-click (Windows) or Control-click (Mac) the name of any selected video track, and select Locked.
– or – 
*   
Locking or unlocking a video track does not alter the lock status of individual clips. If a clip was locked before you lock the track, the clip will still be locked when you unlock the track. However, unlocking a clip in a locked track will not allow you to edit that clip. It will behave as if the clip were locked until you unlock the track.
*
You can Edit lock or Time lock individual Video clips. For more information about locking clips, see Locking Clips.