The concept involves storing a database of advertisements on the PVR. Then when you play back a recording, the PVR detects when there should be a commercial break and inserts an ad. Each time you watch the same show, you could see a different commercial - it might even be targeted to your viewing habits or your region. This way you don't end up watching promos for television shows that have already screened, or commercials for sales that have already finished. It sounds like a Tivo, except rather than ensuring you don't miss your favourite shows, it ensures you don't miss the network's favourite commercials.

One of the biggest threats to television advertising revenues is the ad-zapping button on some PVRs, such as those from Topfield, which lets you skip forward in 30 second increments. Television networks are powerless to stop people doing this, which is why they've started running advertising material over the shows themselves. They also do things like start shows late, and regularly change the schedule, to make it harder for people to record them.

According to Microsoft's patent, an advertisement is screened during playback whenever the device detects the signal indicating a commercial break. Playback could be "at any speed in a forward or reverse direction, such as fast-forward, rewind, skip-ahead, and skip-back". It's not actually made clear at what speed the commercial break would play. If a recorder using Microsoft's system can detect when you're watching a commercial, you can bet there's no way you'll be able to skip the commercials or perhaps even fast forward them. So you're back to the old days, where you got up and went to the toilet or boiled the kettle during the commercial breaks. Microsoft hasn't patented a way to stop you doing that, yet.{moscomment}