In spite of the video, when the time between blocks is big enough most of the time there is a clear winner and there are not long lived forks. (Except the cases when the blockchain was forked on purpose.)

The part about exponential complexity does not make sense.

It is also weird that they draw a blockchain where the nodes forks can collapse later. Bitcoin can't do it, but Ethereum has something like that with uncle chain rewards. I'm almost sure that part of the graph it is a lucky coincidence, not a deep understanding of the different chains.