To do video editing, the processor of the system should have at least 4 cores that support Hyper-Threading like Core i7 4790/4790k or Core i7 6700/6700k. The even better solution is to get the equivalent classes of Xeon processors like Xeon E3-1275v3 and above and also use ECC rams to ensure maximum stability during rendering for professional class editing. If you are just starting to do video/multimedia editing, a Core i7 class processor/a supporting motherboard should be a good starting point. Some of these software also uses GPU accleration, so you may want to consider to add a professional graphics now or later after the build.
If you have a lot of budget, I suggest to build a system with Core i7 5830k that has 6 cores and 12 threads that will make editing even faster than the Core i7 4790 and 6700 series processors.
Finally, get some fast SSD with a lot of capacity, starting at least 512GB. For lower budget, get something like Crucial MX200 512GB or 1TB version. Do not get any SSD with TLC technologies that mean the SSD will burn out faster. If you have a tons of budget and do go with a Core i7 58xx series processor and a supporting motherboard, I highly recommend to get a Intel 750 series SSD either in 800GB or 1.2TB capacity. These fast SSDs combinded with a fast 6-core/12 thread processor will make your editing fly.
Finally but not last, get at least 16GB of ram as the starting point since ram is so cheap now. Add another 16GB to make it 32GB as you advance to edit video files that are getting larger due to 4k and other high definition formats.