Watch the Mo' Modal Solo online guitar lesson by TrueFire from Play Rock Guitar 6: Soloing Approaches
Mo' Modal Solo - Variations is a video guitar lesson presented by Jeff Scheetz and is sourced from Blues-Rock: Secret Sauce.
Instead of trying to go over every mode and all the theory that comes with that, I'm just going to show you how you can add a couple of notes to the familiar minor pentatonic scale and voila' you have a modal sound.
The Allman bros have used the Dorian scale in so many of their songs over the years. Their stuff is a good place to start developing your ear to hear Dorian tonality.