Now, like you, I came close to shedding tears when watching -- not for the same reasons that the Double Rainbow guy did (he was actually wailing) -- but rather because I (like you) was laughing so hard. Absolutely hilarious.
In retrospect, however (and after putting aside the fact that his reaction certainly may not have been solely induced by the rainbow itself but by other "natural" stimuli), the basic thrust remained -- i.e., this guy was marveling at the sheer beauty of his surroundings. Yes, true -- his reaction is a bit over-the-top -- but he was certainly living in the moment. He was certainly taking in the beauty of his immediate surroundings. He was certainly not rushing off to find the next big moment.
And, there is a certain lesson to be learned there. Take time to stop every now and then -- appreciate what you have. It is extremely challenging to do, but it is an important thing to do nonetheless.
(Okay -- but still -- the video is absolutely hilarious!)