Bill mentions it at the 15 minute mark [1]. He says he's the biggest funder of various carbon capture technologies, liquids, solids, you name it. He then explains that it's 2 orders of magnitude non-economic and will have to be 10x the size of the current fossil industry to succeed at the rate people are saying is needed.

[1] https://www.youtube.com/watch?v=d1EB1zsxW0k&t=900s