I have yet to see StageVideo work in way shape or form that is useful for mobile development.
The first problem is that StageVideo is not available on most of the platforms I develop on and deploy on. Here is a summary:
Macbook Pro, Flash Player: available
Macbook Pro, AIR Runtime: unavailable
HP corporate laptop, Flash Player: unavailable
HP corporate laptop, AIR Runtime: unavailable
iPhone4: available
iPad2: available
HTC EVO: unavailable
ASUS Transformer: unavailable (*)
(*) On the ASUS Transformer, StageVideo at first says it is available, but then recants as soon as a live stream is attached.
The second problem is that the new StageVideo.attachCamera method is broken. For details see this thread:
http://forums.adobe.com/thread/1050172
The third problem is there is only one stage available on the iPhone and iPad. This makes it immpossible to display both the video from the camera and the video from a stream with hardware acceleration.
The fourth problem is that hardware accelerated decoding of a live stream does not work on iOS. The Adobe AIR docs state (and I have observed first hand) that I must use H.264 if I want hardware accelerated video decoding on iOS:
http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/media/StageVideo. html
"AIR 3 for iOS uses the StageVideo object for H.264 video with hardware decoding, with limited supported for NetStream functionality. AIR 3 for iOS also supports On2 and Sorenson codecs through the StageVideo object. This support does not use hardware decoding, and it does not limit NetStream functionality."
However, my observations and this thread suggest that live streams of H.264 do not render on iOS:
http://forums.adobe.com/message/4336274
The net effect is that hardware decoding of live video streams is not a reality on iOS.
So in the end, it looks like I am stuck with software-based rendering and decoding of video on most mobile devices.