Interesting idea, I think the footage would look out of place and look kinda weird. Perhaps the dialog could however be salvaged and used to fill in parts in the movie. Perhaps playing it over a long scenery shot or something. As far as recording this you can use a program like fraps to record whatever is on your monitor.

Also on another note, isn't there a fan edit of all 3 movies combined into one? I believe the Laserdisc box set was the basis that already interweaves all three. Then I believe he took some scenes only shown on the television airings. Perhaps even more. This makes for a monstrous epic that I would love to see.