The guy riding the Honda motorcycle shown in the video makes good use of duct tape and some plastic tubes. With those, he makes some sort of dual snorkelling air intake and ensures that no water gets into his exhaust pipe. So, the next thing he has to focus on is to keep on throttling and make sure that the bike goes in a straight direction.
It's pretty creative. Using this method, he successfully managed to go through the flood despite its three-feet depth. What an engineering mind he had for such an unfriendly condition. Imagine how many people you could possibly help with such a DIY flood kit.