Hello Janos,
Yes, I also noticed a "glitch", but I believe it is due to the netbook used in the tests. I believe that a better computer can solve the problem.
The camera used was a JVC and the setup is this (it's in portuguese, you can use a Google translator): http://painelglobal.com.br/talk/destaque.php?id=dat_20111105-081723.incxxadministrador_20111105160930
I'll put the weather forecast for the moment of firing.
About the performance, i believe will not have problems. Ustream is a very good and rarely crashes.

Many thanks for report!