After digging around in the GSVideo sources I realized that the asynchronous loading isn't part of GSVideo itself, but of the underlying gstreamer library. So no easy way to get around it . Instead, here's a wrapper class for loading all frames of a given movie. It's still asynchronous and a bit of a hack, but it works.

1. import java.util.ArrayList;
2. import processing.core.*;
3. import codeanticode.gsvideo.*;
4. 
   
5. public class DemoApplet extends PApplet {
6. 
   
7.     public class WholeMovieLoader {
          
           protected PApplet parent;
           protected ArrayList<PImage> frames = new ArrayList<PImage>();       
           protected boolean loading = false;
           protected GSMovie movie;
          
           public WholeMovieLoader(PApplet parent) {
               this.parent = parent;
           }
          
           public void load(String filename) {
               if (loading) {
                   throw new IllegalStateException("Already loading a movie");
               }
              
               // We need the parent reference for GSMovie's filename resolution to work
               movie = new GSMovie(parent, filename, 10000);                       
               loading = true;           
               frames.clear();
               movie.setEventHandlerObject(this);                                       
               movie.play();                               
           }
                  
           public void movieEvent(GSMovie movie) {           
               movie.read();   
               movie.loadPixels();
               frames.add(movie.get(0, 0, movie.width, movie.height));
              
               if (movie.time() == movie.duration()) {
                   loading = false;               
               }
           }   
          
           public boolean isDone() {
               return !loading;
           }
          
           public ArrayList<PImage> frames() {
               return frames;
           }
       }
      
       WholeMovieLoader loader;
      
       public void setup() {               
           size(200, 50);
           background(255);
           fill(0);
          
           loader = new WholeMovieLoader(this);
           loader.load("insert filename here");       
       }
      
   
       public void draw() {   
           background(255);
           if (!loader.isDone()) {
               text("Loading video... (" + loader.frames().size() + " frames)", 10, 20);
           } else {
               text("Done! Loaded " + loader.frames().size() + " frames.", 10, 20);
           }
       }
   }

It seems that GSMovie.length() and GSMovie.frame() don't really do what I think they should (return the number of frames in the movie and the current frame's number), but perhaps I misunderstood. GSMovie.length() simply returns 0 for me all the time, and while the output of GSMovie.length() changes I don't understand it.

By the way, here's a similar thread.

Thanks for posting your Movie Loader.

Thanks for the clarification!