Man, when Riot Games does something, it doesn't tend to do things by halves. Take The Music of League of Legends - Volume 1, the massive album featuring 15 new and classic tracks from the game. Not only did they record this thing with ridiculous production values, they've also made a 40 minute documentary to go along with it, which you can watch right now.
As for the documentary, well you can watch the whole thing on YouTube. It's 40 minutes long and kinda super dramatic for a docu about recording music, but it's worth watching, particularly if you're invested in League of Legends. It's actually really well made, which shouldn't surprise you because -- yep -- Riot Games doesn't do things by half!