My Problem:

I am currently learning 3dsm from video tutorials. I want to be able to pause the video and take screenshots at important intervals, so i dont have to reply the video over and over again. This always worked fine for me, and wasnt a problem. Now when i take a screenshot the capture just moves about in psp, i can even press play on the video and maximize psp and the video carrys on playing in psp in the area i captured. I can move the box and resize it in psp and the image moves out of the confines of the capture. When i go to save the image it just comes out blank?? what on earth is going on. Any suggestions would be great.

Video type is avi, Some videos i can screencap from, and others i cant. Is this a codec problem?. Is it not possible to screencap images from videos?