How to Change Media Streams on Your Land
There's two types of media streams you can change. One is radio or audio only stream, the other is the media stream, which you can use to play movies or display web pages. Many in world devices can automate this for you, but if you would like to set it up manually, navigate to About Land, and then click the Media tab.
Click set, from there you can plug in a web page, or a url to a movie on the web. I can't really tell you where to get these from, but SL is good at auto-detecting the file type. After you finish that, drag and drop the texture you want to watch the movie on to the Replace Texture area. Everything you see in SL with that texture, should have the media stream on it.
This is similar to the Media URL, except you can plug MP3s, or radio stations that winamp uses (shoutcast and compatible).