Can't just play the movie in a while loop? Like this....
while (current_frame <= desired_end_frame)
{
play_movie
}
end_movie

to make it restart
currentframe = where_you_want_to_restart_it
{
while (current_frame <= new_desired_end_frame)
{
play_movie
}

of course I didn't use the real commands, but I hope you got the concept.