Hello,
The configuration will depend on a number of factors. For example:
1. What video conferencing protocol(s) and ports are you using?
2. Does the ASA use NAT/PAT?
3. Where are the end points in relation to the ASA's interfaces?
For the most part, you should just be able to allow the traffic through your ACL. However, if you're using NAT, you'll need to enable the appropriate inspection engine on the ASA to allow the firewall to translate the embedded addresses in the payload and open pinholes for the necessary child connections.
Depending on the protocol/device vendor, you may also need to adjust the ASA's timeouts so that connections are not prematurely closed during a long call.
Details on the commands for all of the above can be found in the configuration guide, but let us know if you have any specific questions:
http://www.cisco.com/en/US/docs/security/asa/asa84/configuration/guide/asa_84_cli_config.html
Hope that helps.
-Mike
