In toto, the video he made is correct on the facts, except it glosses over one key fact — the press conference was basically exactly what people are demanding of scientists day-in and day-out with regard to scientific outreach. It is imperative that we “dumb down” science to an extent, to communicate its importance to people that otherwise couldn’t care less and would demand the programs be cut for being useless. The paper itself may have underwhelmed him, but he has no leg to stand on when he attacks the press conference as far as I’m concerned.
By my understanding, the press conference did actually explain exactly how they figured out that arsenic is used in the bacteria where phosphorus would be normally. So we have that “direct structural evidence”. Maybe not for DNA specifically, but if there’s a significant lack of phosphorus in the sample, that’s pretty good evidence all by itself that the arsenic in the sample is being used in its stead. At that, there are already very good bits of direct structural evidence of arsenic-based structures in existing, so-called conventional life. So, where’s the beef of his complaint exactly?
The original “hype” for the press conference was that the discovery impacts the search for extraterrestrial life. If this is wrong in any way, I’ve yet to hear it from anyone claiming this is just hype for NASA.