What does a laptop need to work perfectly for gamings?

What does a laptop need to work perfectly for gamings?

I'm trying to get a new laptop, because I'm tired of my old, old, computer.
And I want to know what to look for so that I can download games without it freezing.
Also, I want to know what to look for so that I can watch HD videos on Youtube without the video stopping or freezing.
Thank you.
If you have any more recommendations or advice on what laptop to get, please tell me.
I'm planning on getting a 648(?) GB Sony Vaio one.