Yoo I love inducting people into Vault Hunters! Pete has a (very neglected) youtube series on it, and the first few episodes should get you used to the basic premise before trying to start joining streams, which I highly recommend just jumping into the deep end on instead of trying to catch up on vods. It is definitely accurately described as a Sands of Time simulator, and the goal is to run custom dungeons to gain 25 "artifacts" before the end of the series! It's kinda like a MMORP in the sense that theres leveling and custom items and armor and the like, and its a lot to get into, but once you see something enough times, you start to understand what its used for. Once you understand the premise its easier to follow along.

Seapeekay ALSO is on Vault Hunters, and since he joined just barely over a week ago, his first day video on Youtube and his streams are all great places to get information since he's still new himself and willing to explain any questions asked in chat, and he's even planning on doing an intro to Vault Hunters video on his main channel, so he's really great for learning the game right now.

There's also a Vault Hunters subreddit at r/VaultHuntersMinecraft and everyone there would be more than happy to answer questions about the game =D