Laptop to use as a coaching aid

Hey, everybody. I'm a gymnast and gymnastics coach, and I'm looking for a laptop that will mostly be used as a coaching aid. I'll be running Kinovea (a video program) on it with the video on a 20 second delay, so that I and the kids I teach can take a turn and watch ourselves afterwards. I'll also be watching streams and doing light gaming on it once in a while, but nothing intensive at all.

As an aside, if anyone knows of a cheap alternative solution to delaying video, feel free to mention it. I don't need to record, just watch it on a delay. There's an ipad app that will do it, but that would be a significant investment anyway, and I can get more use out of a laptop. I've also heard of using a dvr, but I'm not sure if that would be much cheaper when you include the cost of a television.

My budget is a max of $600. I want it to last at least a couple of years, but cheaper is definitely better. Size doesn't matter, and standard resolution is fine. It will almost always be close to an outlet, so battery life isn't a huge issue.

I live in the U.S., and prefer to buy from Amazon or Newegg. With black friday deals coming up however, I wouldn't mind buying from anywhere that a good deal can be found.