Add clips using video-only or audio-only mode
By default, whenever you add clips from an event to the Timeline, all of the video and audio components of the event clip are included in the edit. However, you can also add just the video portion or just the audio portion of event clips to the Timeline, even if the event clips contain both video and audio.
Make video-only or audio-only edits
To set the edit mode, do one of the following:
To add just the video from your selection to the Timeline: Choose Video Only from the Edit pop-up menu in the toolbar (or press Shift-2).
To add just the audio from your selection to the Timeline: Choose Audio Only from the Edit pop-up menu in the toolbar (or press Shift-3).
The edit buttons in the toolbar change their appearance to indicate the mode you selected:
Add clips to the Timeline as you normally would.
The video-only or audio-only clip appears in the Timeline.
To return to the default (video and audio) mode, choose All from the Edit pop-up menu in the toolbar (or press Shift-1).