I use my Ipod touch and Ipad to watch dvds I own away from the house (car, plane, etc).
The ipad works great for this. You need to use dvdfab to rip it to your PC, then handbrake to convert it to a file the ipad will read. It's kind of a pain, but nice to take with you.
As for video editing,
You will be way happier on your mac or pc, then syncing to your ipad. The cpu power to render or splice together things with a decent preview is beyond what the Ipad can realistically do. I run a dual core cpu at 3.4 ghz with 4 gb of memory on a raid 0 disk array. My renders still take 20-30 min per hr of video. So, do that on an Ipad????? It would be "go" and then come back tomorrow.