You think "movement" matters in a working terrier? Well it does! Only it's not the dog's movement that counts -- it's the human who has to move off the sofa, and move out of the driveway, and move into the field with a shovel in hand and a terrier at his or her side.
That said, I will say this about movement: two legs on a dog is probably not enough. A dog can certainly work with three legs and one eye. But two legs seems to me to to be a bit short on leg. That said, I am willing to make an allowance that there may be exceptions and I will not hold fast to my prejudices for reasons soon to be revealed.
No, the dog below is not a terrier, but if a terrier like this ever does show up, I will be happy to take it into the field, where I have little doubt it will do quite well.
This is a repost from November 2007.