I already knew that Bitcoin and similar digital cryptocurrencies were basically a version of 19th-century bank-issued currency, only 19th-century bank-issued currency, only without as much security. And that they featured the same basic problem as the gold standard. And that they can be hacked, although technically I think it's the "blockchain" platform on which it runs rather than the Bitcoin itself that gets hacked. And that they are heavily used for criminal activity and require enormous amounts of power to "mine". Weaver reinforced all that and added to it.
A slide that comes up at 18:00 in the video says that Bitcoin alone, not counting other cryptocurrencies, uses as much power as all of New York City. He also says that only three Bitcoin transactions can be processed per second *worldwide*, which is incredibly slow and inefficient compared to systems currently being used by banks.
Previously I had thought that the blockchain technology might be useful for some kinds of record storage. But Weaver argues that even this is unlikely. (Actually, he pretty much dismisses it entirely.) He makes the cases that other digitial platforms already being used are more secure, effective, and efficient than blockchain for document storage and verification purposes.