As for video editing, i will just be editing my gopro2 video so will the Fx-8150 really make a difference? or will i be ok with the AMD Phenom II X4
because with your suggestions adding the Fx-8150 and doubling my RAM the total of my build comes out to around $640 after rebates and my budget is $550 maybe willing to go to $600
That's a quad channel memory kit for the X79 motherboard. You can always use 8GB(2x4GB) of RAM for starters and add more later if you feel that it's not enough. If you're budget is limited, the cpu you choose will be fine. Sure the 8-core cpu will be faster, but the phenom II X4 is a good choice for that budget. There's also the option of overclocking to make your cpu faster, but if you're into it you might want to get a good aftermarket cooler.
If all your doing is basic home movie editing, little more than splicing footage together, the Phenom II will do just fine. There wont be a real difference between the CPU's in gaming.
The difference between the FX-8120 and FX-8150 is that the 8150 is a higher binned chip (ie, higher quality) that comes with a faster stock speed. The chips are otherwise identical.
However, the 8150 "should" overclock further than the 8120 due to it being higher quality.
So if you are willing to overclock, you could take a gamble and get an 8120 and see if you overclock it to some good speeds. Or play it safe and get an 8150 that is faster out of the box, and "should" overclock further than the 8120 would be able to.