I don't know which model of HD's he's using, but my Samsung SP2504C won't fit if I wanna install it the same way like he did.
The HD is 2.6 cm thick (like most ones) and if I want to install it the same way, I'm forced to move it a couple of cm towards the motherboard tray, so that I'll still be able to close the right side panel.

Distance between front bay and side panels = 2.5cm.