Bob Harper's Totally Ripped Core

Anyone else done / doing this DVD? I'm enjoying it (in a holy-hell-this-might-kill-me kinda way), apart from the burpees, always broken by burpees. The problem is I feel nauseous after it and sometimes see wee bright spots. Is it that I'm not fit enough to do this yet?

I run 3-4 times a week and cycle my commute daily but this is more intense than my usual exercise. I don't have breakfast until after, should I maybe try eating before? I've always preferred exercise on an empty stomach but now I'm not so sure it's the 'right' way.