I would like to create a mask, and move the subject within
 

Can I do this?

I would like to create a rectangular Mask, so it appears like a window on the left of the screen, then two more across the screen so I have three windows total. Now if my subject moves about in any of the windows I would like to keyframe the background to keep the subject centered.

Can this be done or is it a job for After Effects? I am pretty sure it can be done in Premiere as well.

Thanks in advance

It can be done just like you say -- set up the rectangles, and then keyframe their positions.

The most basic way is with a cookie cutter, but you don't have as much control over the size and shape of the rectangles as I'd like and as you'd probably need.

But if you use it, you can keyframe the size and position right in the cookie cutter editor box.

Probably better, there's also the beizer mask in the pan/crop tool. You can draw precisely the mask you want and keyframe its shape and position over time. The keyframing is done in the pan/crop tool.

What Vegas doesn't have is a pixel motion tracker, for pinning a mask to a particular pixel . . . but you don't seem to be looking for that, anyway.

I know I can move the mask, David. I would like to be able to create that mask, (a specific size and more control than the cookie cutter) let say the mask just stays in place and I want to move the clip left, right so its like I am looking through a window.

In PhotoShop, if you "paste into", you can move the background any way you want. I am trying to do just that in Vegas.

Then what you want to do is create your mask for whatever your foreground will be (the wall?), and then put your background (what's outside the window) in the track below it. Then, you can move the lower track around with either track motion or the pan/crop tool without affecting your foreground.