FaceFlow is another one. They a put out an app on bb10, om not sure if it's made it to the plybook yet though. It does work in the browser from what I hear.
You can use Faceflow on the Playbook and I have found it to be quite good. I have had much better results on this than either AOL AV or REEL PORTAL. Although there not an app yet for Playbook - I have used it with Simple Browser with no problems on PB. I assume the stock browser would work just as well.
You can try yourself with PB and a lap top. Just log on and send an invite and then open with the supplied link on the other device as a guest.
I have high hopes FF is going to support PB and extend this to multi platforms