It's a variation of the non-slip loop knot () , close to this but I don't run the tag through the overhand knot until after I've wrapped the tag around the tippet three times. I'm probably tying it incorrectly but it's a knot that works for me and I feel like it's bullet-proof (even if it is wrong). Sometimes I get the loop really tiny, sometimes the loop is 3/4" long. I prefer shorter than longer but I doubt it makes much difference. I use flouro tippet for anything submerged and mono for dry flies and emergers.
Are you wrapping the tag around the tippet on fly side, or rod side, before passing it through the overhand knot?
Interesting. I tie mine like he did it but I also do the "improvement" at the end like an improved clinch, where after I pass the tag through the overhand knot, I then pass it through the loop I just made doing that.

