Personally
Well if gaming is the main deal go with AMD all the way, they can definatly take a majority of video editing also.
Here is a suggestion on a good mobo if you prefer Asus
http://www.newegg.com/Product/Product.asp?Item=N82E16813131540
Basically everyone has their favorite in a motherboard manufacturer, but truth is everyone of the better companies now a days makes a decent board. Asus, Abit, MSI ect.... Just basically check and see if the features are right for you.
But the board that I posted basically has it all and from reviews read is a great performer.
has all the features you could ask for.......
Now on the CPU choice: Its hard to put a CPU up on the table again without knowing your budget. But I will list a few and let you decide in the end.
Athlon 64 3800+ is a dencent CPU and will take just about what ever you can give it. Great gaming CPU but might struggle a little in the video editing department if you give it any kind of demanding challange. But overall is a great CPU. Cost is about $373 OEM
http://www.newegg.com/Product/Product.asp?Item=N82E16813131540
Athlon 64 4000+ would be the best all around CPU for the money. Will give better frame rates than the 3800+ but will kick some real **** at demanding video editing due to its full 1MB L2 cache where the 3800+ has only a 512k cache. Is at the same level of the FX-53 CPU wich retails for 100's more.....
Cost is about $445 OEM and if I had the extra cash to spare this would be the CPU of choice.
http://www.newegg.com/Product/Product.asp?Item=N82E16819103529
Athlon 3500+ is about as low as you would want to go in a high end system.
Although it packs a mean punch for gaming and is just a few frame rates shy of the 3800+ it would lack as the 3800+ for video editing. But dont get me wrong this is still a hell of a CPU for the money. And would still get most people that dabble in video editing but live to game, by. Retails for about $272 OEM
http://www.newegg.com/Product/Product.asp?Item=N82E16819103532
Truth is you can spend a lot more money on the Athlon FX series and new Dual core Athlon 64's but can you see spending 7,8, $900-$1200 on a cpu that in a year or 2 is gonna be worth $150-200 ? When you can basically do just as good with a CPU that costs less than 1/2 the price.
Video Id say go with a nvidia 6800 GT or ati X800 wich price is going to fall dramatically with the release of the nvidia 7800 GTX.
http://www.newegg.com/Product/Product.asp?Item=N82E16814150091
however these are all just suggestions and in all you should do some review comparison on the componants and decide what will fit your needs the best.
Any other questions... this board is open for your service.