WHY webcam does not work behind firewalls anymore...?

that is really annoying. earlier versions worked excellent behind firewalls, even two of them. Now these new versions does not work anymore. MSN and Skype works perfectly without changing firewall settings or opening extra ports which is security risk. What ports, how many of them needs to be opened...grrrr.. Yahoo sucks nowdays... even error reporting service does not work at all. "failed to load error report to servers" well no one can't make complains if it does not work.. very wise. Software firewall creates dymanic rules when launching Yahoo as long as application is running but hardware firewall does not. so that is the problem. MSN messenger was same kind earlier but Live version works perfectly behind firewall.. I think yahoo has gone step backwards with this..... can anyone tell me for real how and what ports are those, not any guessing and not only persons who use some leaking so called firewalls. Thank you.