I love me some HIIT!!!
I don't know about DVDs, but the website I use has a ton of free workout routines-they don't try to sell you anything and they give you complete workouts!!! I don't remember the site right off the top of my head, but if you google HIIT it for six pack abs you'll probably find the right one.
I did the second one they posted first-should have done the first one first....will kill you, but amazing workout!