Yeah, no. When Greg Mankiw, probably the foremost conservative economist in the world, endorses Yang's UBI, then it's probably worth considering seriously:
https://www.nytimes.com/2019/09/27/business/yang-warren-taxe...
https://www.nytimes.com/2019/09/27/business/yang-warren-taxe...
It does not read like an endorsement — just an assessment that Yang's plan is better than a plan he describes as unworkable (Warren's).
In the Youtube, he says: "My own view is that a universal income financed by an efficient tax, something like a value added tax, might well be worth considering" — hardly a full-throated endorsement.
Has he said anything else that is more positive? Or more specific with regard to the amount of UBI that he thinks would be appropriate/efficient? I wouldn't call either of these things an endorsement.
"The plan is just a version of the negative income tax. Milton Freedom first proposed it...and as a student 40 years ago I thought it was a pretty good idea. And it turns out I wasn't alone in that judgement...In 1968 a 1000 economists endorsed a negative income tax along these lines. What Andrew Yang is proposing is a version of what these 1000 economists endorsed back in 1968. Could 1000 economists all be wrong? Laughs Well yes they could. But I don't think in this case they are. My own view is that a universal income financed by an efficient tax, something like a value added tax, might well be worth considering. And I'm one of the signatories...of a plan to do something similar with a carbon tax."
As in, the $1k/month thing is too big, and he thinks we should consider doing something smaller. How much smaller? We don't know for sure, but I doubt economists would support a carbon tax that would approach the level of $1,000/mo for every adult in the US. The primary purpose is to internalize the externalities of pollution, not to generate revenue.
The fact that an economist thinks a concept is worth considering is a far cry from saying they are endorsing a specific instance of one of those things. It's one thing to say he endorsed the concept. It's another thing to say he endorsed the plan. He didn't.