I don’t know what they use, but it is probably one of the Ultimatte packages.

MPEG is a heavily compressed format and one of the first things to go is color information. so, you might have a hard time pulling keys. A lot depends on how your MPEG is encoded.

In any case, there are two software keyers that I am comfortable recommending. The first is the Primatte Keyer distributed by Red Giant Software and the other is DVMatte Pro distributed by DV Garage. Both are specially designed to work with compressed footage and can overcome some of the limitations.

Both of these keyers work as plugins to your editing software. DVMatte Pro works with Final Cut Pro and Primatte works with Mac and PC editing suites.

No software can overcome badly lit and shot footage so take great care with your setups to minimize the issues you have to deal with in post.

I hope that helps,

The Go-to Guy!