Hi all! After trying to explain to people multiple times and not finding what I thought was the most thorough of explanations in regards to BoM - I created a video on it. I know there are a few out there, but I did a play-by-play on how it works. Lots of folks have watched it and really liked how I explained it, so please feel free to take a peek. I hope it helps out!
https://www.youtube.com/watch?v=xpLeHdVVqXw