I got it to where I was happy. I dropped it off to a buddy at a shop to double check. I will post what comes out of it.I read through this post, and watched your video and looked at the picture of the plug. Sounds to me as if it is running OK (better than mine). As for your original question about the fuel pump, you could put a pressure gauge on it while it is running. I believe it should read about 3 psi, but check your manual to be sure. I bought this pressure gauge: 0 to 15 psi range is good for the purpose. A 0-30 gauge might also work if you have one, but I'd say a 0-100 wouldn't.
I've been working pretty steadily on my 2007 arctic cat 500 4x4 FIS, almost the same as yours. Mine also runs rough, and I'd say it is running rich. I have the Dynojet Kit in it. Do you have the stock jets? Have you checked to be sure they match OEM specs?
Try the "more air, less air" test: For More Air, remove the air filter - does it run better or worse? For less air, put a piece of cardboard or some other restriction into the intake airstream - upstream of the carburetor - does it run better or worse?
Finally, have you done a compression test?