This is a few weeks late from me, but I checked out your video. Most of it is good stuff, but I wanted to offer a different opinion on some moves you covered.
F-Throw: This is character-specific, but f-throw can 'almost combo' into Thoron. It's escapeable, but some opponents will fall right into it if they don't jump IMMEDIATELY after their knockback/hitstun from the throw ends. Also useful for getting opponents off stage, even if you aren't likely to kill from that position. This can buy time for tomes/swords to respawn while they grab the edge.
B-Throw: Not just a kill throw; it does 11 damage which is significant, and using it early on in an opponent's life can take them off-stage for edgeguarding. While I do agree its best use is as a kill throw, there's more to it than that.
Nair: You may be underestimating this move. It's actually one of Robin's 'kill' moves in that it does more horizontal knockback than vertical. Get the opponent off-stage and nair them... and there's a decent chance they won't be coming back. You can also use it to poke at opponents by jumping at them, doing nair, and fading back as the nair animation begins. It's not perfectly safe on block, but it is fairly so and thus makes a good poking option.
Dair: Is worth using as it is a fairly strong spike, as you say. Note that dair-spiking people who are on stage is risky business though as this move has a lot of recovery. It's not useless like some think, but it's mostly a spiking tool.
Thunder and variants: Thunder and Elthunder are better than one might think. Thunder is basically an inferior Falco Laser, but you'd be surprised how often a 3 damage plus hitstun move can be useful. It can slow down approaches, interrupt people from slow-to-start moves, and I think 3 damage is enough to send back a Dedede Gordo. Elthunder is 9 damage and fairly easy to hit with, often making it a good choice for slowing down Captain Falcon and other rushdown-happy types.
Various comments left on the video already pointed out the Thoron "hold B for more damage" thing so I won't go into that.
Other than these points, the video is pretty good and I picked up a few ideas from it; d-tilt as a combo starter didn't occur to me until you mentioned it.
