Thanks for the response. I have Photoshop, but I am not sure how to use the crop tool in Vegas. I have use the transparent/child-parent feature. However, I am actually trying to take a video of lets say a person, crop out that person & put them in a different background. Any ideas?
You're using crop in the colloquial sense. The crop tool in Vegas affects the frame as a whole. You can crop the top, the sides, the bottom, you can zoom in, you can flip and rotate the image, but the relationship of what is going on inside the frame you create does not change. The frame you end up with still be rectangular of some shape.
What you are trying to do is not crop out, but cut out. As jetdv suggests you want to use masks to cut out the person from the background. Do a search for tutorials about using masks. You may also want to search on "The Kid Stays in the Picture" which is the title of a documentary that used a lot of photo tricks. I know one user recreated them using Vegas and Photoshop.
Also if you want to do this often, check out the book Photoshop for the Non-linear editor. People have been raving about it.
If you want to remove just a person and put them in front of a new background, you have to make it possible for Vegas to identify what's foreground (the bit you want to keep) and what's background (the bit you want to get rid of)
To do this, shoot the person in front of a single colour screen - usually green or blue, then Chroma Key can be used to make the background transparent. Lighting is important - do a search for Chroma Key and you'll find lots of tips.