As with the video of Craig Smith's talk, I'm posting this without any attempt to summarise or comment. If I think of anything incisive to add having re-watched the video, I'll post my thoughts at a later date. For now I just wanted to make the video available for those who missed the talk, or wanted to see it again.
Tom's talk lasts a little over an hour; the rest of the time is given over to a Q&A session. The graph to which he refers is this one: