iPad iOS 4.2 and Macbook Pro airplay

Hi all,

I currently have installed on my iPad iOS 4.2 beta 2, which includes the ability to stream audio and video to devices such as the airport extreme and Apple TV.

I have recently purchased the second generation Apple TV and am loving it so far.

I have two questions:

1. My iPad at the moment can stream audio to the Apple TV, but not the video as shown in the keynote presentation of the Apple TV, will these abilities become available when the full version of iOS 4.2 comes out or am i doing something wrong?

2. My computer at the moment won't stream any audio from the videos that it is playing through either the Airport Express or the Apple TV, which i find weird considering that the iPad can do it.
Will this also be available when the iOS 4.2 comes out? because i would love to be able to listen to the movies that i play through the good speakers instead of just on my macbook.

Thanks in advance and any help would be much appreciated.

Julian.