can't say anything about the PS2 power supply especially since there is absolutely no other information about it in the specs.
If you plan on maxing out high end games on a resolution of 1920x1200 or lower, you really won't need anything better than a Radeon 7970 or a Geforce 670.
If that isn't exactly what you are aiming for, you can check out GPU Tier List | FinitPC
for other options. Average prices are based on Newegg.
i7 is fine since you plan on video editing and have a really high budget, otherwise if you feel like you aren't an above average video editor and wanted to save some cash, the i5 3570K is just as good for gaming and still does very well with video related tasks.
750W PSU is a bit overkill unless you are open to the possibility of using SLI or Crossfire in the future or if just don't really care about the price since your budget is high then its perfectly fine. If you stick to one graphics card (which I would ultimately prefer to avoid any possible microstuttering problems and God knows what else) you can easily get away with more of a $100 PSU with around a 600w limit even if you do plan on overclocking as long as it has two 6+2pin PCI-E connectors for high end graphic cards.