Pretty sure AirPlay for video and photos is not going to be in the 4.2 release, audio only for now. If you listened to Steve Jobs carefully on the conference call 2 weeks ago, he said AirPlay video before the end of the year.
This makes sense since we haven't seen AirPlay video in any of the 4.2 betas. Sorry to disappoint.
Stop spreading FUD. AirPlay video is included in 4.2. It's just the Apple TV is currrently running iOS 4.1 which only supports audio and there are no other AirPlay video devices on the market.