If you scroll to the bottom of any lesson page with an MP3 the new player has a little downward pointing arrow to the right of the track title. That is the start download button.

Also if you click on the question mark you get the option to "turn on the help features". This will give you mouse over pop-ups to show you what the various buttons and features are on the player.

As far as Doug's videos, notations and tabs you should contact him in the instructor forum and you might want to email the Guitar Tricks support personnel.