Not all apps are supporting video streaming via AirPlay. I some cases, if you enable video streaming in another app like you tube, then go in the unsupported app to play the video, it will stream anyway. But it's a matter of being lucky.
For Netflix, apple tv 2 is supporting it directly without the need for an iOS device. Do you have the apple tv 1? Don't know if this one does support Netflix. But if you have a Wii, for example, Netflix is also supported on some game console.
Seems like sound streaming is always supported but as for video, it always depends on the app supporting it.
If you actually need to rely on the iPad to play your Netflix movies, then you can grab a tv out plug as Netflix does support this feature.
VicoPad addict!