Obviously, nothing beats one on one instruction, but if you aren't in La, that can mean few and far between sessions. The videos I have, I transferred to DVD, and that has helped a lot. I see videos and DVDs as just a piece of a learning process. If nothing else, a reinforcement, or even a cobweb duster.
As far as instructors go, my experience was with fiddle workshops. I walked away from each with something of value, but it is rare to find that perfect player/instructor combination. I found many players had a difficult time getting across to the class, maybe because they just play the stuff without thinking about it. A good example was Ralph Blizzard. I don't think he ever played the same thing twice, and though his playing was stellar, in a workshop, it let to lots os frustration in his classes. Great for moderately advanced players, but not for any level below that.
So, my opinion, look for someone with patience, someone who can articulate, someone who can see your level instantly and procceed accordingly.
But even having said all that, the other piece of the puzzle is emersing yourself in the music, and realizing what level you are at. You wouldn't want to sign up for an introductory math class and discover it's Steven Hawkings lecturing on worm holes. Well maqybe for entertainment value.
Steve

And Steve's teaching at Augusta this year, along with the other members of the Mamou Playboys. They and Keith Frank/Soileau Zydeco are the house bands.

I think one can learn from videos.. if they are done slowly enough, song broken down enough, notes held long enough, and some silence between held notes helps.

The good teacher sees learning in segments.. dosed from easy to more difficult..builds on previous knowledge.. and incorporates old moves into new songs and contexts.

Good teaching recognizes process more than product.. ( Marc Savoy's vids are the product.. Dirk Powell's vids are about process ). ?

virtuoso playing does not mean good teaching, but doesn't exclude learning. A mediocre player who can teach well is a better learning resource. IMHO.

Glenn