Im not too familiar with the demands of video editing on a processor, but I dont think there is much reason for you to have over 3.2 GHz. In my experience the only programs demanding enough for you to even dent 3GHz is something like autocad, or a very complex flight simulator. But like I said, im not too familiar with video editing.

As far as the motherboards facilitating better/faster CPUs in the future, it really depends. Ive seen a bit about the VAIOs being stubborn with new hardware, but that might just be a few people's thoughts.

Also, RAM is very important (as bad karma said). Im running 512 DDR and its buttery smooth, I even committed about 30 percent of my RAM to helping out the processor in a pinch.