Separate the video from the audio
When you record in Camtasia, the audio and video are packaged as one clip. You can separate the screen video or camera video from the audio into two separate tracks for editing.
To separate video from audio
Control-click on the clip and select Separate Video and Audio.
The audio and video separates into two separate clips on the timeline. NOTE: Moving the audio and video tracks on the timeline, may cause the audio and video to become out of sync.