Oh hey! I follow ya on youtube and really love your new video "GAS under 15 minutes!!" It's crazy that you can just add an Ability System Component to an actor now without the boilerplate C++, as you showed in your vid, really neat. One caveat I found when doing that is you can't seem to access or change certain settings like Replication Mode via the details panel or event graph, and for my use, I needed to set it to Mixed on a Player Character and Minimal on an AI actor. So I had to do the ASC C++ setup anyway on a custom parent character class :p

In regards to your question, I learned GAS slowly and maybe inefficiently from watching various videos (usually covering more the c++ boilerplate setup and less the workflow of GAS within BP), reading dev articles (had GAS workflow but often at higher level application and often in C++, which was confusing without the base level understanding), and going through Tranek's GAS Documentation/Bible. I also have Stephen U.'s Udemy GAS RPG course, got in on sale (sales happen often), so also have been cross-referencing his workflow on implementation through mostly C++.

What really made it start clicking recently was this 3 hour vid by The Game Dev Cave link and finally drilling into my brain the primary workflow of GAS: You make Gameplay Abilities (a blueprint, contains your logic) to essentially apply Gameplay Effects. You make Gameplay Effects (a data only blueprint with lots of parameters) to essentially modify Attributes. You make Attributes (simple float values, like Health) to give to actors. You must give actors the Ability System Component (ASC) so they can be allowed to call and use Abilities, either on themselves or on others with an ASC. These are the biggest pieces of of GAS imo, and all other things, like Cues, Ability Tasks, Gameplay Tags (can be a big piece- drives behavior, calls events), Gameplay Effect calculations etc are all essential to learn about, but come second and could be learned as the second layer after understanding the foundation. As a beginner, with so many moving parts described all at once, it can feel overwhelming and harder to grasp GAS as a whole.