That's actually a really nice video, Saito... it captures quite a few different elements and showcases a number of things. Hopefully it can put an end to the arguments that want to suppose properly implemented reactions will slow down combat; this is an excellent example of how they don't.
I actually have another video of a lower level fight in Solasta (from an earlier EA phase where they had the controversial homebrew rule where attacks against enemies in dim light imposed disadvantage - this ended up being axed rather quickly) where a boss actually uses Fly, Shield and Counterspell against my party. It also has a brief showcase of using ready action ranged attack to launch arrows at enemies during their turn, when there weren't any viable targets during my own turn before.
(But the boss also tried to 1 VS 1 my Greenmage Wizard and lost horribly because Flaming Sphere is actually a hard counter to his flying shenanigans, which was probably why the enemy AI was banking on trying to break his concentration with Scorching Ray. The one Scorching Ray that did hit rolled too high for my Wizard to counter it with Shield, so the game doesn't bother asking you if you want to cast it there, as it would be essentially wasted anyway.
Also my Wizard having the highest bonus to attack with his bow shots but having the lowest actual rolls seems like it's going to be a recurring theme for me.)
It's so nice seeing a "use spell" button to show all cantrips and prepared spells.
It's also great seeing a reaction for Divine Smite and Attack of Opportunity.