Except he doesn't explain how to pay for it as far as I can tell. He has four funding sources that don't come close to adding up to the $3 trillion he would need to fund a UBI. The $800 billion for a vat is incredibly generous but even assuming that he can only come up an additional $500 billion by assuming that everyone will prefer a UBI over other government programs. He also assumes $100-200 billion will be saved by the government due to lower costs of other government programs.

Even assuming everything adds up that still only gets you to $1.5 trillion, you still to come up with another trillion at least! Borrowing the money will result in the US running the largest peacetime budget deficit of any developed country ever. A budget deficit of 15% of GDP would be at least 3 times what the budget deficit was at the height of the Reagan era. It's simply disingenuous to claim that this is par for the course for advanced economies. It isn't.