Two easy solutions, neither is extremely pretty, but both are easy and workable.

1) Use tracks 1 and 2 only during that clip. Build the rest of your project on tracks 3, 4, 5, etc. (This is what i do.)

2) Add a solid white generated media event to track 1 wherever that clip isn't. This saves on tracks, but it's messier in the long run.

Chienworks:
Isn't it simpler to use the parent/child relationships than what you suggest?

I do use parent/child tracks for this. The problem is that the parent/child relationship affects the entire pair of tracks throughout the entire length of the project. If you are masking track 2 with track 1, then wherever track 1 is black you won't see anything of track 2 ... including the parts of the track outside of where you want to use masking. It doesn't matter whether the tracks are parent/child or not.

Thanks,
I placed the Multiply Mask and the clip to apply it to on the very bottom of the project and it worked. I can now see all of the video project. I had previously tried the parent child and it stilled affected the entire video. I had also previously moved it lower in the project but never to the very bottom. It just did not seemed right for the entire project to be affected where there were no clips. However, there may be a good reason for that that I don't understand.
The only thing that bothers me is how I have to chop the film exactly where the multiply mask is or you see nothing (the effects clip is half the length of the background and there for anyplace where the effects clip is not the video is black (or I can place the white on the track as suggested). It seems like I should be able to apply Multiply Mask directly to the clip instead of the track.

Thanks again for the both of your inputs.

Yes, there is a very good reason. The mask compositing mode multiplies the pixel color values in the mask track by the pixel color values in the track being masked. Think of white as 1 and black as 0. Since anything muliplied by 1 (white) is itself, wherever the mask track is white you'll end up with the image on the other track showing through. Wherever it's 0 (black), well, 0 times anything is 0, so you'll see black. Now ... what's on the maks track when you don't have an clips there? Why, black, of course (or your project's current background color, which defaults to black). So when you don't have a clip on the mask track everything gets multiplied by black and ends up black. Hence my suggestion to add generated white to the track everywhere else.

I suppose it might be possible for Vegas' programmers to change the logic so that whenever there is no clip on the mask track that the mask is inactive. I suspect that would cause many more problems all around. Maybe a switch could be added that would toggle the behaviour between the two modes. Then again, since it's trivially easy to deal with the current behavior, it's probably not worth the effort.

That being said, there have been times when i wish i could insert "compositing mode markers" along a track and change the compositing mode from point to point. Now that would be swell. :)