Old Nikon lenses are fine with APS-C cameras (and the focus throw and hard stops make them possibly great), but you really need a 17mm or 18mm lens (it's in every "cinema" kit: 18, 25, 35, 50, 85, or the like) and a really fast 17mm is expensive and rare. On full frame, you can get a 28mm f2 Nikkor very cheap and have the same field of view as 18mm on the 7D so Nikon lenses are better on the 5D, imo.
If you can figure out what to do for your widest lenses (look for 17mm and f2.8 or faster) you can use Nikon primes to fill in the gaps as they have great ergonomics and bokeh for the most part. But a 17-55mm IS takes care of 90% of most people's needs, anyway.
The reason I recommend that lens is because if you're using a dSLR you're looking for "dramatic" video and the standard focal length range is 18-85mm at f2.8 or faster, which the 17-55mm IS almost provides, and the IS is great for video. Sure you can tack on longer (70-200) or wider (11-16) but for that kind of material other cameras, like traditional video cameras, are generally as good or better.