Capturing screenshot of movies during playback

I am developing a media player that plays mpeg-4 movies files using Microsoft VB 6 with SP6.

My question is there a way to add an additional function that takes screenshots of movies while playing and saving it in as jpeg/bitmap file in the hard-disk.Plus I wanted to add a shortcut key to my program and when I want to take the screenshot I just press the button.Can anyone please show me how to add this screenshot function to my program?(perhaps show me the source code).

try movie player activex control
http://www.viscomsoft.com/products/movieplayer/