Movie loop until a button is pressed

ok, my problem is that I want an intro-movie to loop until I press a button to play another movie (start-movie), but the intro-movie should stil play until it’s finished and then go to the start-movie instead of looping again.
I don’t know too much about the script-commands, so I have embedded the movies in the timeline instead of using instances and use commands like “gotoAndPlay(“frame”, 1);” at the end of the intro-movie.
Is there a command to tell the intro movie it should play until it’s finnished and then go to start-movie?