I highly recommend 6-string bass guitarist Todd Johnson's "Technique Builders" DVD for bass guitar - he uses a 4-string bass on the whole DVD, so don't worry that it might be for 6-string only.
I've had it for years and still go back and watch it and pick up nuances and/or refine/relearn something each time.
I don't know if he sells the DVD on his website anymore - looks like maybe just the download version there, but it looks like you can get the DVD from individual sellers on Amazon (maybe eBay, too?).
BassBooks.com has it available with the book that goes with it - I have just the DVD and never saw any need for the book myself, but that's JMHO.
It is the only "physical technique-specific" DVD for bass guitar I'm aware of & includes:
•Right and left hand ergonomics
•Floating thumb technique
•Right hand muting
•Hammer ons & pull offs