You think correctly. I thought of a few pedantic objections to the
video. Your comment about distinguishing light before and after the
CMBR is one of them. The video could have been more clear about that.
But in the main, its explanation is a good one IMO for the meaning of
the observable universe.
The video explicitly describes Glenn's quotemine as a superficial
understanding of how light behaves. The expansion of spacetime adds
to the distance light had to travel since the beginning of the
universe. What makes it even more complicated is that the expansion
speed has changed over time.
You're entitled to your own opinions.
You're not entitled to your own facts.