Informative and helpful!
I am learning AS, so I found this very useful. You covered a lot of the things essential to a platformer, and more. I found that this answered a lot of the questions I had about Action scripting(big relief)!Thank you!
---------
However, I found a strange glitch. ( i don't know if it was the tutorial or my coding) but if you placed the character in an area between two walls, the character would slowly be pushed to the left by some unseen force, until the character fell through the wall on the left. This small bug has really been messing up my platformer. That is the only problem I've faced with this tutorial.