I have made a couple of these, they are pretty easy to make.
BUT! In the tutorial he states that you should, "... cut one of the wires". I would, however, recommend using the HOT side of the cord, rather than the Neutral. Install the inline fuse and the fluorescent starter on the HOT side; on a regular old household brown extension cord, the Hot side is the smooth wire, and the Neutral side is the one with ridges in it.
The drawback is that the flickering is not as subtle as something like the Lights Alive Candle Flicker box; you can't adjust the flicker rate or intensity. But the advantage is that these are cheap and easy to make.
Let me know if this helps. Hope it does!