Direct TV Commercial Star Trek-How did they make Shatner's mouth fit the words?

Answer 1

An application developed at New York University, known as Video Rewrite, uses computer animation to match lip movements with the new voice track.

Answer 2

I think his part was filmed especially for that commercial and then spliced it into scenes from Star Trek VI. When they are showing Shatner, you only see the backs of random crew members - never any of the other main crew members.

Answer 3

All they had to do is super impose his mouth over where his mouth was in the old footage.