What do Unchained cards do?
Well this is simple to answer, they float when they are destroyed and dont care if they get banished or go to the GY so long as they are destroyed. They also like to link your opponents monsters away for your benefits for the best board breaking. Spells searches and the traps SS from GY or destroy 2 cards, no matter which way they are all good to use. Only 1 "brick" card in the archetype but the unchained monsters can special from hand or deck so its not too bad.
Why Blind 2nd?:
Because this deck can link your opponents monsters away that is a good start for disrupting your opponents monster and clearing there beat sticks easily. Also Kaiju monsters are very good as you can tribute your opponents monster to the link with your own Kaiju, this is an ideal "combo" unless they have multiple difficult to out monsters. Also this deck uses some special spice, Super Poly. This is even more helpful to remove difficult monsters and works wonders in this deck, although targets are few and far between. Handtraps are essential for going 2nd, this is completely upto you which you run and what you can afford, i personally like the 2 Ash + 2 Ghost belle but you can change these about to suit your needs. (i know the video shows 3 Ash but its still a deck that is evolving and changing based on the meta)
Can this deck go first instead?:
Technically, Yes. you can change your side deck to run trap trick and cards that are better for going first like IDP and solemn cards, however i prefer going 2nd.
Deck Video:
https://www.youtube.com/watch?v=bH7-2i-jAnI&ab_channel=AstroKnightYGO