Absolutely you'll see it bouncing slightly. The reason is, the belt will stretch and contract slightly as the engine speeds up/slows down. The tensioner provides two different functions:
- Provides tension to keep the serpentine belt tight during operation
- Takes up slack which might be introduced as the belt gets older
Well, there's a third thing to consider, as well:
- In a lot of vehicles, helps keep the belt in alignment
Tensioners should be good for well over 100k KMs (and most likely a lot longer than that). After just 2KKMs, you shouldn't have a fear about this ... even the bearing. The belt should be good for somewhere around 100KKMs (but check the belts manufacturer's recommendations). There are even higher quality ones made with Kevlar which will last even longer.
As far as the noise ... those are turning bearings in there. You will hear some noise!
You really shouldn't have any fear of what you have as long as it was installed correctly. I'd assume since you've made it 2KKMs without real issue, there's not going to be. The tension markers seem to be aligned correctly, which makes that good to go as well.