You can easily stream YouTube or Vimeo videos with Worship Extreme.
Create a new cue and set the background type to "Web Video". Click "Set Video" and paste in the desired video url and click "Save". Next time the cue is fired, the video will start playing as your cue background.
To play a USTREAM video full screen, open the video in a browser and choose the "pop out" icon in the bottom right of the player. In the pop up window, copy the url and paste that url as a web page cue background in Worship Extreme.