Aaand... Looking at their landing page[1] I can see they've chosen to go with a horizontal page layout. Because they use a non standard page layout they have a black stripe bumping in and out of the viewport instructing the user that they can/should scroll. This is quite a common layout among artsy portfolio themes[2].
Has anyone ever tried to sidescroll a web page lately? On my Yosemite MBP with latest Firefox/Chromium I just get a jitter and no movement. Sometimes the scrollbar moves in the wrong the direction and then dies.
Moral: what is tried and tested usually works very well.