I feel like some of the above video was from some of Veritasium's previous videos because they look somewhat familiar to me.
With that being said, the video does a great job explaining what happens in fireworks.
Dr Derek starts with making rudimentary black powder (gunpowder - not the modern, smokeless version as Derek explains at 8:30) starting with the initial recipe from ancient China and moving to a more modern 75/10/15 ratio of carbon/sulfur/charcoal and then to a commercial, modern gunpowder.
From there, it's onward to testing the effects of container strength on the size of the explosion - first with a simple, cardboard tube then with a reinforced tube. He then brings in a fireworks manufacturer who explains the cardboard, spherical shells of actual fireworks and the method for launching them.
Then a bit about the methods of triggering the shells - showing black match then the craft-paper-encased quick match - including how to waterproof that trigger and how that trigger moves into the fireworks shell itself and lights the stars to produce the color and flash.
Speaking of the stars, they move into the creation of the different colors due to metallic salts and showing the individual spectra of those elements due to their electron configuration. The expert does then use some methanol to step things up a bit. (Remember kids, don't use methanol...ever.)
And the video wraps up with footage of a drone flying through the fireworks finale. I'll admit...that's pretty cool and should absolutely be watched in high res and expanded size.
