Look out, Mike. You're standing at the edge of a very deep rabbit hole! How far down do you want to go?
When the Groove3 people offered a 30-day free trial, I spent most of that time watching Kontakt vids. They were pretty decent, but there are a lot of them and I found myself dozing off a lot. Creating libraries isn't nearly as much fun as composing with them - it's a little too much like my day job, like work. But those Groove3 videos were pretty alright.