The Movie Player processes the script-channel text after it has finished drawing the current frame to the playback window and displayed the frame the required amount of time. The script-text processing is the last thing the Movie Player handles before moving to the next movie frame. With the following exceptions, you can use any MCI commands and options in the script channel:
You cannot use the notify flag in any MCI command. If you need to pause playback until a certain command completes, you can use the mciWait script-channel command. The Movie Player uses the notify flag to implement the mciWait feature.
You cannot use auto-opened MCI devices in the movie script channel. All MCI devices used by a movie must be explicitly opened.
The Movie Player provides limited support for the “all” device name. You cannot use commands such as “play all,” but you can use the “close all” command. If you use the “close all” command, the Movie Player closes all MCI devices opened by the movie (not all MCI devices opened by the application).
Your movie should include commands to close any MCI devices it opens. In any case, when the movie file is closed, the Movie Player closes all MCI devices the movie opened. It must close the devices, because it's possible that playback will be stopped before the movie reaches the frame containing the close command.