gdgt

By default the skip ahead button goes 30 seconds and the skip back goes 10 seconds. There are ways to change those values but not built into the media center interface.

This is not a smart commercial skip it just moves forward or back by the set time. There are some 3rd party applications that can be used to scan the shows you record to mark the commercials automatically and allow you to skip them by default or to skip them by hand. I used one of them and it tended to get it right most of the time with maybe one mistake in an hour show but the interface to force it to show the section that had been tagged a commercial by mistake was too much for my wife to accept so we went back to just using the skip ahead. typically 8 presses will get you to the right general spot.