For those of you who do not like bsplayer to cap your vids (I personally don't like it and removed it from my system about 2 minutes after installing it), you might want to consider using infranview:
http://www.irfanview.com/
For those who don't know, infranview is a free picture player and is my personal favourite, but it also plays video clips.
To cap using infranview, first set the preferences:
1) open infranview
2) hit 'c'to bring up the 'capture setup screen' and set the settings as in pic #1 below.
3) hit start button on 'capture setup screen'
4) play vid in infranview
4) when you get to the part you want to cap, hit 'ctrl' + f11 on your key board at the same time and the captured pic will be saved to your desktop as in pic #2 below.
5) you'll see that there is a little toolbar at the top of the pic: to remove it go to the top left corner of the pictue, left click and drag down the right bottom of the pic - a square will now be over the pic section.
6) go to 'edit' in the top tool bar, hit 'crop'
7) go to file and hit 'save'. There is your cap (see picture 3)
It takes less than a minute to go from playing the vid to saving the cropped pic.