Checked your link and got a table of contents for several features, but I am uncertain of what you are really refering to.
If you want real webcasting, PHP is probably not the tool for the job.
Go with C++ or Java since they both have very mature support for streams, which is what you'll need for a real webcast since a webcast is a stream of binary data that can be joined at any time, just like turning on the TV in the middle of a program.
Mind you, PHP is comming out with streams, but you will need to recompile PHP with streams support (and sockets as well I imagine) in order to use those very experimental and as of yet undocumented features.
