Simly put:
1/We want a javascript that will randomly pick an swf to load from an XML file
2/You'll also make the .fla which will contain on the timeline:
a) a movie clip background always looping
b) a streamed flv
c) a movie clip synchronized with the flv
d) a very slim progress bar of the flv
e) discreet buttons : mute and skip (that will go to the final image of the flv)
3/You give us the right html code to insert in the joomla article
you can see the idea of what needs to be done here [login to view URL]