ah, the error is at second loading... probably you haven't closed the myMovie...
while (myPort.available() >= 10) {
//Video Code:
String command = "";
for (int i=0;i<10;i++){
command += myPort.readChar();
}
println(command);
[color=yellow]
if (myMovie!=null){
myMovie.stop();
}
[/color]
myMovie = new Movie(this, command+".mov");
//myMovie.setSize();
myMovie.play();
}
but maybe the Video class isn't supporting the opening/closing of video: so you have to have a Video variable for each of your code.. try with the code in yellow, if not i'll work out something 