In some of these videos I play easy third position. In other words, not what is best but what is easiest for a new 3rd position violinist. I shift up and down easily and would normally automatically choose positions that work well both musically and to avoid strange string crossings, etc.
When you choose your positions, try to pick them to avoid awkward shifts, audible shifts, unnecessary shifts. Try to avoid unnecessary string changes if possible and when possible, without sounding bad, stay in position until you can find a safe, quiet place to shift.