A couple of years ago I tried on about 7 pairs of running shoes in runners need, and spent a few minutes on a treadmill in each of them. I was really surprised at how different they all felt, and ended up buying some that I didn’t expect to.
Since then I’ve had two more pairs of the same shoe. I’m not a serious runner – I plod about 20k a week. But for me, it really seemed that you just have to try a bunch of pairs on, on a treadmill.
(The whole gait video thing seemed to me to be bollocks. Different people in different shops have recommended everything from very supportive to very neutral to the new hotness super cushioned shoes. So I just politely nodded, ignored their view, and went with what felt good to me)