Err... he managed to take a NES, open it, take out the pieces, but them in a different case, and add in a fancy light that looks like a toaster making bread. GENIUS!!!!!!!!!!!!!!!!1111one
Seriously, PC builders do this exact same thing all the time. It's just that the "On" buttons are easier for them to put together.
Also, redoing the power cord wouldn't be hard, I'm fairly sure he'd just have to Eff around with the Power Supply (though it would require some soldering, methinks). The A/V jacks were probably the easy part, I be he just cut a hole, put some AV jacks in there and hooked them to the NES, making them a sort of extension cord.
And lastly, HOLY SNIKES, WHERE'D HE GET THAT OTHER NES TO BE SO BRUTAL TO? (I'm talking about the beginning, when he was throwing a hammer at the motherboard)