I have AirPlayer on my iPad under iOS 4.2.1. It works fine in conjunction with uShare DLNA server and Windows 7 embedded DLNA storage feature. There is a problem when I try to watch a movie or play a music from my NetGear Stora NAS.
When I try to connect to my NetGear Stora NAS, AirPlayer successfuly shows folders and files. But when AirPlayer opens a movie, it shows only waiting cursor and does not start to play.
Switching QuickTime option ON helps a little. By this setting enabled I could watch several movies of formats compatible with QuickTime.
Netgear Stora NAS has a last available firmware installed. I can play any content through it's DLNA server by Windows 7 MediaPlayer and WD TV Live! device.
Please check this out. AirPlayer is a great application. I hope you'll fix this issue.