Typically anybody that makes more than a few million per month on the internet and is not under the protection of the authorities for stuff like this has by now found out about the dark side of the net.
We have not seen any attacks on the video infrastructure but we're small fry. Let me ask a much larger site using wowza and get back to you on that one.
"If there has been we haven’t noticed. Taking down one wowza server wouldn’t cause us any problems. They would have to take down 5+ servers for us to notice."