Hi. I've noticed that there are a few DVD's out there (for example, Sting's "All This Time" concert DVD) that say they are dual layer, but there is no layer switch. I don't understand how that can be. If it's possible to have a dual layer disc with no layer switch, then why doesn't every studio manufacture all dual layer DVD's with no layer switch (or at least one that isn't detectable). I've seen some DVD's where you can't tell the switch is there, but there are some that it's very noticeable. Anyway, please educate me on this. Why have a layer switch if you don't need it? Thanks.