I build a PC like I'm going to game on it and this would lintel lots speed and efficiency. For what you want you can build your own but if your not looking to do all that then you can buy a PC off the site you listed.
I saw the a computer on the front page "CyberPower X58 Configurator" has a nice set up but if your doing video graphics then i would recommend the "power mega 1000", don't think you will out grow that anytime soon.
A few things to keep in mind, RAM you can always add later as they get cheaper, Hard drives, you can add external or build a server down the line ( my friends always look at HD space when buying a computer thinking it would make it better...which it wont ) so buy a good processor and mother board... maybe a good power supply as well and your cooking. The Mega series i mentioned will give you RAM, processor, Memory and a hefty HDrive.
Well the price difference between the two models are expensive but thats because there adding more features ( the processors alone are $60 differences )The differences between the i5 2500K and the i7 960 is the thread count, it has 4 more to total 8 and other non essential features for your application....for that price. What i mean by this is if the price difference was say $100 between the two setups they are offering you then yes get the i7 machine but there adding more options to USB bus and hard drives....etc to the $1900 package.
Remember I'm basing this off what you are using it for, if you said i want to game would recommend something different....but your not going to grow out of this.
Don't hesitate to ask
A 2500k would be the better option. No, the only difference isn't the thread count. Both have 8 threads, both are quad core processors with HyperThreading, that is the same. The 2500k has a much better, more efficient architecture, so much so much so that it is level, performance wise, with a 980x, even though it costs just a third of the price. Then, factor in that socket 1155 is still going to have more CPUs released, which will improve the longevity of the system because it can, in future, be upgraded without the need for a new motherboard, CPU and a fresh install of Windows, makes it even better.
On that second point, by going the socket 1366 route, which is what you advised, and later saying "I want more power, let's upgrade", a completely new copy of Windows would be required, because buying prebuilt = OEM OS = new chipset means the key will no longer work as it will see it as a whole new system.
He would also have to do a lot of configuring with the CyberPower system, because as standard it will come with junk to make it cheaper. It will have a poor power supply, and money wasted left right and centre.
In short, he would be better building his own on a socket 1155 system. It will last longer and be much better value for money.
CPU:
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115072
Mobo:
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157229
Memory:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231426
PSU:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817151094
Video Card:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130660
Case:
http://www.newegg.com/Product/Product.aspx?Item=N82E16811119216
SSD:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820167050
Hard Drives: 2 x
http://www.newegg.com/Product/Product.aspx?Item=N82E16822152245
DVD RW:
http://www.newegg.com/Product/Product.aspx?Item=N82E16827136238
OS:
http://www.newegg.com/Product/Product.aspx?Item=N82E16832116716
Total: $1420
Total after shipping: ~$1440
You are getting there:
Much better quality parts
More powerful/faster parts with scope for easy upgrades
A system more suited to your uses.
Note though that there is an SSD and 2 hard drives.
The SSD would be there for Windows, games and frequently used programs only. You would never save pictures, videos, music, files etc to it, only those frequently used programs. The reason for this is because an SSD is a hell of a lot quicker than a conventional drive, so it helps immensely with boot times and load times. Those which I mentioned you shouldn't put on, they already load extremely quickly from a hard drive, and so wouldn't benefit from the speed - it would be wasted space and wasted read/write cycles for the SSD.
The 2 hard drive would then be put in RAID1. I assume, as you do video editing a lot, you store a lot of videos, and some of these you would need a solid back up of. RAID1 will put the same data on both drives, effectively backing up as you go, so your data is always safe. If one drive fails, the other has that data intact, so you have that safety net.
Those drives would be used for your videos, infrequently used programs, pictures, files etc. Things that are either storage data, programs that are used rarely, or small programs that won't benefit from the speed of the SSD a whole lot.