I thought it would have been earlier than this for you! Even more impressed with your in depth knowledge of the game given that timescale. I know it's 10 years, but I've been watching for about 6 and I can barely name a passing concept lol.
it must have been the 2010 season because (i just checked) that was the first time since the 90s that the NFL and the superbowl were being broadcast
and dont worry - i really struggle with passing concepts too - really struggle with LB and safety keys too
i imagine those are the kinds of things that any randomer who played the game in school could probably understand (even if they suck at them)
in the same way that i can turn on the tv mid-game during any sort of rugby and immediately understand in detail what's going on all over the pitch at once because i grew up watching and playing it during my formative years and that stuff just sticks more easily
the detailed stuff i've picked up about the NFL is mostly based on draft stuff - which is more about projection which means that route concepts and stuff aren't as crucial to the evaluation of a player - so much of it is traits based and the minutiae of how i guy "wins" and that stuff i've found pretty easy to learn
watching the ravens running game every week though has massively helped my understanding of how running schemes work