You can block streaming audio/video but you'll need to research what ports they are using in order to block them. They are always changing so you'll have to find out what they are using.
For example, deny the said ports in the below example:
access-list 101 deny tcp any any eq 1720
access-group 101 in interface inside
This will stop the connection initiation from the inside going out for the H323 initiation for Multimedia Streaming traffic.
Additionally if you want to block that traffic for good, then you can also remove the fixup H323 which you might have in there, which will not give them the way for making the connections on dynamic ports and would not be allowed through.
Hope that helps.
R/Yusuf
