A laptop with a discrete graphics card and a good cpu , something 2.5Ghz to 3.0Ghz. You didn't give us a budget amount that your working with , so you may get suggestions that are not in your amount that your willing to spend.
If your budget was say , $900 then you could consider this one;
That's great for games I suppose since it has dual GT 650m GPUs...
To encode video you do not need a discrete graphics card especially if the program cannot take advantage of using it improve the encoding performance. Most programs do not. Since encoding video is very CPU intensive, i recommend a laptop with a quad core i7 "QM" CPU.
I would get something like the following 15.6" Acer which has a quad core i7-3632QM @ 2.2GHz. It also comes with a GT 640m if you want to play games from time to time; good enough for medium graphics quality.