Within your firewall, you will need ports 80 (HTTP) or 1755 (UDP, TCP) opened and free of filters. You will also need to allow calls to the "63.250.215.*" range of IP addresses, and the following URL domains:
Certain firewalls, such as Norton Internet Security, also contain ad removal features that may be enabled. You will need to disable or configure these to permit streams from Yahoo! LAUNCHcast.