Hmmm....I just want to give my 2 cents. I'm using GOM Player (which likely most of you won't use). If you want to take screenshots by using this application, you can right click on your mouse. Go to the video and then click the advance screen capture.Voila! Click all you want and you'll get your fav screenshots.
I'm using GOM Player too and it's the best way of taking screenshots I've ever tried.