You may find it helpful to review the introduction to the earlier Opening up the sequence using Splice with Sync Locks enabled recipe as it includes an overview of Sync Locks.
In this recipe, let's imagine that, as assumed earlier in the chapter, you're editing a scene of a comedy television program.
The goals in this example are that:
You want to extend only the video of segment 64B/18 (pictured in the next screenshot). It's a close-up shot of one actor's shocked reaction to another actor's line of dialog.
You want to push the other segments (shots) in the sequence down, so that you can later add in the sound of the audience laughing underneath the video of the shocked reaction shot.