Note that this document gives a warning -- and you should heed it -- about making sure to use FR1/SP2 with Citrix Metaframe 1.8 -- and how using UPD port 1604 and opening up high ports on the server is a security risk. In general, the more ports you open through a firewall, the more potential that you open ports vulnerable to an attacker. This is why the TCP browsing mentioned in the article mentioned above is a better way to go.
Regarding the webcast, you're going to have to find out from the webcast host what ports need to be open and then determine if you want to do so.
This was first published in August 2003