He is good at explaining physics, but he has enough goofy opinions as to make all his judgments questionable.
He blames Republicans for being anti-democracy. I guess he disagrees with showing ID to vote, but he did not explain.
He has typical knee-jerk liberal opinions.
He says that special relativity requires that there be no preferred frame of reference for time, although he seems to know that the cosmic microwave background radiation suplies one.
He believes in eternalism, and that he has no free will.
He admits that string theory is not falsifiable, but defends it anyway, because today's philosophers have declared Popper obsolute. He says string theory provides some high-energy thought experiments, and we would hate to discard it just because it is pseudo-science.
The most revealing question was about how Many-Worlds theory explains the double-slit experiment. Some many-worlds advocates would say that every time a particle reaches the double-slit, the universe splits into two, with a particle going thru each slit in each world. The interference pattern we see is the result of interference between the worlds.
He does not accept this, and prefers to say that the beam is a wave, and so gives an interference pattern.
One does not need quantum mechanics or many-worlds to give that explanation. Sure, all waves give interference patterns, in a setup where the wave interferes with itself.
This admission shows how terrible many-worlds is. If many-worlds cannot explain the double-slit, then it cannot explain anything. The double-slit is the most elementary example of quantum mechanics. It was Feynman's favorite.
It is true that many-worlds cannot explain the double-slit, or any other experiment. There is no way to count the splittings, assign probabilities, and calculate the interferences. It is all silly science fiction.