For someone in their mid-40s, in good health, that never had any type of self-defense training... what would be some recommended sources (DVDs, books, or other) where a person might gain some knowledge of defensive skills and techniques?
Military style techniques?, martial arts?, combination? ... I have no idea.

Mostly, I would plan on using a fireman to defend myself.
But, what happens in a situation where a gun/rifle is not available, and a hand-to-hand confrontation is on?
I have no desire to be a "fighter", but I think it would be nice to have some knowledge of defensive techniques, and develop some physical defensive skills.