Yeah, of course that the 3930k will outperform the 3820.. but you can get a 3820 for $230 on micro center if you leave near one.. you also have the best price for the 3930k there, which is $500.. still it's $270 difference, even if you can get a $100 cheaper motherboard, you end up with $170 difference, and then it really depends on budget and not choice.
I myself have a 3820 for video editing (and games also) and I'm quite happy with it