Video Techies: On AV receivers, why is there a bandwidth associated with switching the (typical) two component video inputs? It would seem there are active electronics associatied with switching between the two inputs. Why not just passively switch between the two? As a follow up, why is there a quantum leap in price to go from 2 component video inputs to 3 or more? Is there a fundemental reason why most AV receivers only have 2 component video inputs?