This argument comes up a lot, and the two sides boil down to this:
JRB is technnically correct in terms of who has to show first; (though more and more rooms have the you must show to win provision so he would have to show anyway to win in those rooms); and those in the "information is paramount" crowd think you should always insist on seeing the other hand, because info is that important.
The other side is those who think that the social aspect of the game is paramount, and that it is way more important to keep players happy, and not embarrass them by making them show a poor attempt at a bluff, then it is to see what they are bluffing with. So in that regard, Hellmuth is correct. He plays in big cash games with business owners like the owner of the GS warriors, so he understands how many powerful business people don't like to be embarrassed or shown up, and play for fun, so it's important to keep them having fun.
I have personally been in a game where a rich businessman fish was donating all night; then he tried a lame bluff, and got called. the businessman said "you're good" and the guy insisted the businessman show. The BM said something to the effect of "I said you're good. Are you calling me a liar?" The guy insisted on seeing his cards, and the BM racked up and left to go play BJ.
On a smaller scale, I see this all the time. THe guy may not rack up immediately, but tightens up, and the mood at the table turns sour. I play 2/5nl live fulltime; and in a year's worth of play I would estimate that maybe only once a month tops would someone say "you're good" and then actually have the winning hand as some sort of angleshoot. So almost always, it is accepted etiquette if someone says "you're good" or "I missed" to just show your cards and win the pot. As someone in the video mentioned, if you insist on seeing the cards, and it turns out the other guy missed seeing a flush or straight, then you lose. IMO the small nonzero chance of that happening is worth preventing more than any "valuable" info I'd get from a 2/5 player showing a losing hand.
So as you can see, I am clearly in the camp of let the guy muck and win the pot, and keep everyone happy at the table. IME this is way more "+EV" than insisting on seeing a guy's hand.
But having seen this discussion many times before, I predict no one in the "info is paramount" crowd will be swayed over to the "keeping the game happy" crowd, or vice versa.