I started looking at the video but had to leave. What I got out of it is that there is a point after the Big Bang but before today where Time started. Since time as we know it didn't exist before that event, it might not be technically correct to even discuss it using the word "before" because of the implied baggage. Near as I can tell, this beginning of Lawrencian time is more or less tied to the end of the superlunimal phase of expansion "after" the BB.
However, past a certain point I think it is all quibbling about the philosophical difficulty of answering the question of "If the universe is expanding, into what is it expanding?"
Yes, I know that the issue may well be moot. I'm just observing that there is an elephant in the room. The math says there is no room. The language is, of course, the problem. The use of the term "expansion" carries baggage. So does the use of "Bang" as in "Big B..." And mathematicians are as bound by language as we are.