73:00 - this seems to be a mis-summary by Hanson. I am pretty sure that Norvig was saying that complex models were still useful - not that simpler ones didn't even exist.
The situation is similar to that with compression. If you can compress a bit that is still useful - and it is easier to do than compressing a lot.
Link: overcomingbias.com/2011/07/debating-yudkowsky.html