how do u take a picture in a video

on my laptop, i right-click and press "save image to downloads" and then add the image to fanpop. on my mac, i press shift, command and three to take a screencap of the whole computer, and shit, command and 4 to section out a screenshot.(as seen below)(i chose that because... its right here on the screen XD)

I use a snipping tool. It's very useful for capturing the right moment.

if toi already downloaded some videos, toi can use video players that can capture the video easily, like KMPlayer, SPlayer, and many more. (probably lots of them, above is just an example, i'm using these though)
and i also agree with stlouisfan. toi can use snipping tool too, and also u can use print screen

toi pause it and press the Prt Sc button and then paste it into paint ou something then save it