hahahahahahahahahahahahaha, no way is that a 34 pound gain in muscle, he looks exactly the same size only a little more muscular and tanner.
http://www.fourhourworkweek.com/blog/2007/04/29/from-geek-to-freak-how-i-gained-34-lbs-of-muscle-in-4-weeks/
lol... that looks more like 15lbs of muscle (and thats a generous estimate)
Look again, he is definitely significantly bigger in the 2nd set of pics. As to the claims of how, who knows? If he was regaining muscle and had starved himself prior to the training it is not impossible.
its possible if its not new muscle ... but unless hes 8 feet tall the diff is nowhere near 34lbs of muscle ... my guess is douchebag doesnt know how to do bf tests