Help cutting square in the middle of a video

Question

I did this in the past and I can't remember now to save my life!
I thought there was something called cookie cutter, but I guess that must have been in another world.
I have a video on track one.
On track 2 I have a video that I want to cut a window out of in the center so that the center of the video underneath shows.
How can I do that?
I know it's something easy and stupid but I can't remember. It's late and maybe I'm tired :-)
I'm in Pro CS5
A 4 point garbage matte would have been awesome if I could invert it!
Your help is appreciated, thanks!

Answer 1

@shooternz,
I would normally do that, but in this case it's not going to work for me. I'm nesting the sequence and there's a few more things going on that make that setup not work.
I appreciate the suggestion, thank you.
I work between Vegas / Final Cut Pro / and Premiere to edit different projects depending on what outcome I want and it gets a little confusing some times to remember which one has that specific feature you're looking for and which one doesn't.
Anyway, I don't think asking for a simple inverted mask in Premiere would be too much.
Where's adobe with all this I wonder, because everyone else has had it for years!
So I'm with Jim Curtis, I will join in and request it. For now what I did was go into After Effects, cut the square out of the video with an inverted mask, and brought it back into Premiere. Geez...
There's a transition called "Iris Box" which actually does what I wanted for this clip, but it does it in motion.
If I could have paused that transition and applied it to the entire clip it would have been great.
Adobe should take the mask that's in After Effects and put it in Premiere!
Well anyway, thanks for the help and suggestions.