If I were you, i'd first look at the software package/packages you wish to use for editing/encoding the video, and then build the system around those packages.
I think you will find that most of them are optimised for the Intel platform.
An i7 will give you a boost for encoding with its HT technology, but this is not huge compared to an i5 750/760, and an i5 runs a lot cooler than an i7.
Saying you go socket 1156 then I can recommend the GigaByte GA-P55A-UD4, it's fast and rock solid, and a modest overclock can be had even by a complete novice, safely. With a modest overclock it will out-pace much more expensive CPUs which are not overclocked.
For a graphics card, if you are not a gamer, then don't go for a high end nVidia, as already pointed out CUDA doesn't make a great deal of difference at the moment, as very few software packages can make full use of CUDA.
Also keep in mind. High end CPUs and graphics cards have larger power requirements, and produce more heat, so don't forget to budget for a good quality PSU, and a case with very good cooling. My personal favourite for a case is the Antec 900/1200 series, where ventilation is excellent, and they also run quiet.