In ACID Pro, when you import a video file, it gives you the video track and the audio track - just like a regular old audio track that you would import or record, and you can remove or edit it to your heart's content. I thought Vegas did the same thing - almost positive Vegas Video would do it - I mean, I don't think they would give that functionality to one of their audio programs and leave it out of their video programs, you know? If they did, I would lose a lot of faith in Sonic Foundry... but like I said, I am willing to bet my mom that they allow you to do that in any of their programs that support video.
Brad