Experiences / Security issues about QuickTime Streams?

[Michael Jung]

An Apple user asked to open the port 554 for RTSP/TCP and 6970-6999 RTP/UDP data 
streams. 
These ports seemed to be used for Apples Quicktime Streaming as described in 
http://www.apple.com/quicktime/resources/qt4/us/proxy/

Are their any nown security issues why the e-smith team block these ports, or is it 
only the default value to block all except requested?

Michael Jung