If you are using roVideoPlayer then just before you call the play function and if you are using roVideoScreen then just before the show function.
Example snippet:
roVideoPlayer
player=CreateObject('roVideoPlayer')
* Your code to add content for the player
* Your call to script
player.play()
roVideoScreen
player=CreateObject('roVideoScreen')
* Your code to add content for the player
* Your call to script
player.show()
Hope this helps