It's not that I'm some guy undercover, keeping people from this site but Guitartricks main competitor Jamplay is going to bring out high quality bass lessons somewhere this year. Even David Ellefson from Megadeth is going to do beginner lessons on their website. They are planning on releasing full beginner courses transcending into more advanced stuff and songs.
But those lessons aren't up yet. You should check their website from time to time or subscribe to their newsletter to keep being updated.
Hope that helps.
JJ