I just finished watching the first video (up to turn 40 or so) and I was surprised that you waited as long as you did to start a Settler. Is it worth it to produce so many warriors initially and spawnbust? Sure, growing to the happy cap is going to allow you to build the Settler faster, but it takes some time to get there first.
Prior to DanF5771 teaching us about the spawnbust trick (back when we thought we had to reveal every tile), using warriors was difficult-to-impossible on immortal...you needed archery or a strategic resource ASAP (note Snaaty's guide for emp+ for example, though he's mostly talking about deity). Knowing the mechanics though, most deity starts are OK w/ warriors...
However, it's important to get them in the fog quickly. This allows them to fortify in defensive terrain (forests or better), allowing them to be odds-on vs archers and reducing the total #'s seen. Because of the start location on this map, it was even more effective than usual - the AIs killed the barb animals and I locked out spawns...never fighting even ONE battle despite barbs being on!
But to do that, you need to get them out reasonably quickly.
The other reason you want to grow is to work all your specials. In this case, there was only the plains cow that was a >4 yield tile. Early in the game, the top priorities are settling and working as many improved special tiles as possible and coming up with the commerce to pay for them.
The final reason to hold off on the settler is to get certain techs before you cut down on the slider. The less commerce you have, the more important this consideration becomes. Believe me, maintenance on immortal and especially deity hits HARD after 2-3 cities, if you don't have something other than the palace 8 base

you can find yourself stuck on 20 turns to research pottery or 30 for writing on normal speed -----> that's a bad thing. You want those techs before you crash!
I was able to get away with some extra believe it or not due to the enhanced tech rate of having a riverside flood plain AND settling on riverside wine on turn 1. That 2 extra

across all early techs makes a difference - even with sal's relatively bad starting techs I was able to throw a 2nd city deep into the jungle in part because I'd done enough research to that point to know I wasn't screwed.
Priority changes in extremely tight quarters though, you might want the strategic resource to rush, or you might need to chop like crazy just to get there in time.