This is as straightforward as these kinds of things can get—just run the app and start recording. How-eva: you need to be connected to a computer for this to work at all. This hack can only record video to your PC, so unless you have a particularly small laptop to strap your DSLR to, this could be unwieldy. There's no sound, and without built-in microphones none of these cameras will ever support it. The resolution is good enough—but not HD—at 1023x680 and 25FPS. Automatic focus is disabled, but manual works fine.
The biggest problem is that the hack only supports recording for a few minutes, a limitation that can't be overcome on account of being caused by an overheating sensor. So, to recap: if you don't mind recording three minutes of manually-focused, not-quite-HD video without any sound while carrying a tethered laptop and brûléeing your precious CCD sensor into submission, this is your hack! [CanonRumors via Engadget]