The clicking noise is incorrect... It sounds like more like a lower end running out of oil.. And yes they all should make a noise..
Best thing to do is memorize how your car sounds now, then if you start to hear something different be very concerned. There are alot of people that say that they did not hear the noise, which maybe true, but in all the loose sprocket cam cars that I have seen and there has been several of them they "all" made a noise.
Is it 100% that they will fail? No, not at all.
Here's how it works, the first few cams from each production were probaly ok and will never fail. The kicker is that who has a set of 4 cams that were made from the first set of each production?
4 cams per car, 20000 car equals 80000 cams, there was no order to when they were made nor when they were installed. So you have a better odds of winning the lotto then at somepoint not having them fail.