Those plans will work. But from what I've read about incubators using the dimmer switch instead of a thermostat, you need to monitor the temperature a LOT more (like constantly) to keep within a good range. I would recommend using a thermostat without the dimmer switch. That's just my opinion, though.
ETA: I forgot to mention that I didn't see anything about ventilation on that video. Ventilation is absolutely necessary.
I would use a thermostat instead of the dimer switch. You can get a water heater thermostat for like $10.00 at home depot. that is what I used. Or you can order a wafer style thermostat for I think around $30.00. The wafer should work better. I didn't see a water pan in the plans, You will need that for the humidity and like Tammyd57 said You will also need a vent.
A thermostat is a switch that turns the power to the heating element on and off at a determined temperature. it would go inside the incubator in replace of the dimer switch in the the plans. Its like the thing on your wall that turns your AC on and off.
I built an incubator similar to the gopher-bator, before I saw that page. I've used it to hatch twice and it works very well. I used the water heater thermostat and it held temperatures very nicely without a wide swing up or down. The key to getting stable temps is in placing the thermostat very close to your heat source AND putting something in there as heat ballast, I used 4 jelly jars filled with water.