They use an MPEG-4 video codec to keep the file size down, but either way you're still going to need a mighty Memory Stick to store all those extra clips you'll be recording.
Also, there's this whole format thing about VC1 and how VC1 has emerged -- that's pretty hardcore -- but our codec's emerged as the highest quality even versus the MPEG-4 stuff which if you'd asked people a year ago they would have said there's no chance of that happening and that's happened in a very big way.