I saw there was a post about NYARToolkit here a little while back.  It looks like there is a version of NYARToolkit for processing now available.

I'm fairly new to processing, but it seemed like it was easier to get hooked into a webcam rather than through JMF as required by NYARToolkit for java.  I ran the example *.pde that comes with the download, and it does detect the marker but for some reason the background comes out blue instead of displaying a video.  

After that, I decided to switch over to eclipse.  I made sure I had WinVDig and QuickTime 7 installed in that order.  Then referenced the NyARToolkit.jar and NyAR2.jar files, as well as video, jogl and core.  Finally I referenced QTJava.zip which was found in the Program Files\Quicktime\QTSystem folder (yep I'm running win xp).  After playing around a bit I got the video to display with the marker.  I also copied the data folder into the project folder, and printed out the Hiro marker.

Here is my code:
Code:

package testVideo;

import processing.video.*;
import jp.nyatla.nyar4psg.*;
import processing.opengl.*;

import processing.core.*;

public class processingVideo extends PApplet{
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	
	private Capture cam;
	private NyARBoard nya;
	public void setup(){
		size(640,480,OPENGL);
		colorMode(RGB, 100);
		
		cam = new Capture(this, this.width, this.height, 30);
		nya = new NyARBoard(this, this.width, this.height, "camera_para.dat", "patt.hiro", 80);
		
		nya.gsThreshold = 120;
		nya.cfThreshold = 0.4;
		
	}
	
	public void draw(){
		background(0);
		cam.read();
		image(cam, 0 ,0);
		if (cam.available() != true){
			return;
		}
		
		
		//cam.read();
		
		if (nya.detect(cam)){
			pushMatrix();
			popMatrix();
		    PGraphicsOpenGL pgl = (PGraphicsOpenGL)g;
		    nya.beginTransform(pgl);
		    //noFill();
		    stroke(255,200,0);
		    translate(0,0,20);
		    box(40);
		    nya.endTransform();
		}
		
	}
	
	public static void main(String args[]){
		PApplet.main(new String[] {"testVideo.processingVideo"});
		
	}
} 

For some reason when I uncomment noFill();, I get a black screen (I think the background shows up instead).  I thought I would at least share my code for anyone else wanting to play around.  Not sure what is wrong with the noFill.  The other problem, if I understand the doc file for NyARBoard correctly, is it is meant for a single marker detection only.

Cheers,
David