Henway,
You have several options to choose from with making vidcaps. I personally prefer BSplayer. There may be better overall media players out there, but BSplayer is very simple to make caps. After you install it follow these steps:
click on "preferences"
click on "general" in the menu on the left
make sure the "YV12 formats" box is unchecked
check off the "YUY2 formats" box
below that is "Directory for captured images" where your vidcaps will be saved (choose your folder)
below that is "Image format" (make sure you use .jpg for this site)
That's it!!
Now when you play a video, all you have to do is press the 'P' key and a cap will be saved into the folder you have selected. You don't have to pause the video or anything else of that nature. If there's another player you prefer, just right click on the video you want to cap, then click on "Open with" then "BSplayer".
Hope this helps. Good luck.