Lifextender is pretty simple. It scans the directory that Media Center records TV to every X minutes for new TV shows. All new TV shows are queued up to be analyzed and scanned for annoying commercials. After a show has been analyzed, a new file is created from the original with commercials cut out, around 3/4 the original size. The original show is then replaced by the new, commercial-free show. Rinse and repeat.