D&S Video Tripod
We assume that you are considering the Davis & Sanford ProVista 7518. If this is the case, the ProVista GR18 is a bit lighter and will work well for your video application. However there is nothing else in the line that will provide equal stability and be significantly lighter in weight.
As far as changing the head, this should be a simple screw-on swap since all D&S and most other brands of tripod use a standard 3/8x16 fitting. Good luck, and good shooting, Jason Schneider