That pump noise is not normal, and pump noise on the Hydro series coolers is an acknowledged problem in a small percentage of units ...http://forum.corsair.com/v3/showthread.php?t=107252
I have my H100 hooked up to my Lamptron fan controller, and at 100% (around 2150 RPM), my pump has the same noise as in your video. When I drop it to 90% (1750 RPM) the noise is completely eliminated with minimal impact to cooling performance. Others have used a diode to reduce the voltage with the same beneficial result.
Corsair has been able to reproduce the problem in their lab, which is "a tolerance issue in the ceramic bearing around the pump shaft". Reference: http://www.overclock.net/t/1236923/corsair-h100-h80-h60-noise-grinding-pump-fix/240#post_17333576
They're currently tightening their screening process on their next manufacturing batch and will be providing information on how to RMA your units once it's confirmed they're available in-house without the noise issue. I'd recommend you follow that thread on overclock.net as Corsair George is posting updates there.