I started to test this, but never got a chance to finish.
You could “Capture Audio & Video to seperate files” ( That is in System Settings)
Then when you need to re-digitize deleted the Video.
Change the capture settings to video only and uncheck “Use logged clips setting”
This will re-digitize video only.
The link to the audio may be lost so you would need to the go and “Reconnect” the audio in the timeline to the clips in the Audio Capture Scratch.
It may not be the most elequent way for doing it, but you asked if it can be done and this should work.
Like I said I haven’t tried the whole process, so I would suggest doing a test before you actually capture and edit your piece.
Steve Cohen
Editor
O2 Media Inc.