This video would certainly count as "Voith Kickdown," and definitely makes some nice sounds.
Almost sounds as though those buses could've used an additional gear or two for freeway running. Then again, running higher-rpms on the freeway should at least help to clear up varnish in the engine.
Only rode an NH once on the freeway back in 2007 when the Mandurah line opened; we missed the last train headed out of Perth and had to take one of the freeway shuttles back to Murdoch from Esplanade Bus Port. This bus then decided it didn't want to do freeway duty, and decided to blow a rear tire at Canning Bridge exit.
I was disappointed to have ended up on the NH - there was a Renault artic headed to Mandurah stopping via Murdoch as well. Would've been fun to do the freeway on that!