How do you take video inside of a video game?

[Sabotender]

I've seen these videos on youtube where people have taken video from inside the video game.

How do they do that?

Can anyone tell me or suggest some good site for it?
Thank you.
Thanks guys!

 

[cali stunter]

you need a capture card man

if you have a laptop you need an external and if u have a desktop you can use either