Here's my experience and 2 cents~
We took both the DSLR & video cameras on our last trip. I was in charge of the DSLR, & my husband was in charge of the video camera. Over the course of the trip, I took 1000+ pictures, and he only took 45 minutes of video. Half of that 45 minutes was taped during the safari ride. We watched that part once and everyone was nauseous afterwards!
With that being said, it IS priceless to have the footage of my children meeting & interacting with the characters.
Would I bring both again? Yes. Would I take the video camera with me every day into each park? No. I would selectively choose, based upon my itinerary for the day. It was too stressful to try to juggle both, and the video camera ended up staying in the bottom of the stroller after about day #2. The DSLR stayed on my wrist all the time!