I agree that the 2 DP Vids are the way to start. Next Steve's Vid and Wilson's are terrific. There is a lot of material on both but I think Wilson's lesson on triplets is key to really opening up the fingerboard and helps get that cajun sound. It is also a favorite lick of the modern Zydeco players and gets a nice syncopation in there. Here is my 2 cents. Always play the scale over and over just like DP shows you in the beginning. This will train your ear so you will always get the octave without thinking about it. Then try to pick out tunes and you will automatically play them in octaves. Add the embellishments that you feel and voila, you have your own arrangement. I think it is helpful to learn the chords, 1, 4, 5 in both the push and pull keys and then in the F position and the D position. Play along with CD's and just chug some background using the bass buttons to get that chank a chank going. Also, a key move is to get the G going (on a C box) in both the push and pull. This will help you keep that box going in and out in that endless stream of notes that to my ear really define this music. Steve Riley's version of Flammes D'Enfer comes to mind. That lick that he does really opens the box to your own improvisation once you get it down.