For some reason the below code won't export as a movie. I get a blank Java window which just sits there doing nothing until a stop the Processing script. The code runs fine without attempting to save to a movie.

Can anyone spot where I'm going wrong?
TIA

BTW this is on a Mac (10.5.8)

1. import javax.media.opengl.*;
2. import processing.opengl.*;
3. import processing.video.*;
    
4. float a;
   
5. boolean bExportVideo = true;
6. MovieMaker mm;
7. int MAX_FRAME_NB = 2400;
   
8. 
   
9. void setup() {
10.   size(800, 600, OPENGL);
11.   frameRate(24);
12.   if (bExportVideo) {
13.     mm = new MovieMaker(this, width, height, "movie.mov", 24,
14.       MovieMaker.JPEG, MovieMaker.HIGH);
15.   }
16. }
     
17. void draw() {
18.   if (frameCount > MAX_FRAME_NB) {
19.     if (bExportVideo) {
20.     mm.finish();
21.     delay(1000);
22.     }
23.     exit();
24.   }
25.   background(255);
26.  
27.   PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;  // g may change
28.   GL gl = pgl.beginGL();  // always use the GL object returned by beginGL
29.  
    
30.   // Do some things with gl.xxx functions here.
    
31.   // For example, the program above is translated into:
    
32.   gl.glColor4f(0.7, 0.7, 0.7, 0.8);
    
33.   gl.glTranslatef(width/2, height/2, 0);
    
34.   gl.glRotatef(a, 1, 0, 0);
    
35.   gl.glRotatef(a*2, 0, 1, 0);
    
36.   gl.glRectf(-200, -200, 200, 200);
    
37.   gl.glRotatef(90, 1, 0, 0);
    
38.   gl.glRectf(-200, -200, 200, 200);
    
39.  
    
40.   pgl.endGL();
    
41.  
    
42.   a += 0.5;
    
43.   if (bExportVideo) {
    
44.     mm.addFrame();
    
45.   }
    
46. 
    
47. }