Yeah the lighting is probably what does it but I still think he looks bigger than 200. I'm 6'2 185lbs with only 15 1/4 inch arms I feel like I look nothing close to that. But I guess dim lighting and the shadows mixed with a bottle of oil can make anyone look a little bigger.
Here it is if you want to watch it:
YouTube - 50 Cent - Amusement Park (Launch Premiere)