if u want add youtube video use Youtube button:

how to use the youtube button??
Código: Seleccionar todo
Example if u want add this video: http://www.youtube.com/watch?v=LEX_31yOr5c
only copy this: LEX_31yOr5c
and put this intro de youtube code
[youtube]LEX_31yOr5c[/youtube]
about your question only need add "On Preload" or "On Show" scripts using the _CommandLineArgs "Variable" this value contens what you want...
Example:
if (_CommandLineArgs[1]) then
-- Here put your script, this only an idea
Audio.Load(CHANNEL_BACKGROUND, _CommandLineArgs[1], true, false);
end