My MackBook Pro keeps heating up

Hey guys!

I have a mid 2012 macbook pro 15' quad core i7 4gb ram.(its a refurbished from apple. bought oct.2014) Im trying to record some game play video, using elgato game capture HD, and while im recording my laptop keeps heating up and I can hear the fans. I bought this laptop because a lot of people have said, if you wanna record videos and render them fast, get a quad core i7. can anyone give me some ideas on why it keeps heating up? I thought that having quad core, it spreads the power and enegry of the software you're using(im not a tech guy, so I dont really know how quad core works).