You notice he doesn't use a driver. He rectifies the 120ac to give himself 170v, then puts a number of the 100w (actually 50w) chips in series. I need 10 citizen 1212's for my 379v rectified supply. It's been on my mind a while. Use a 'clean mains' type extension lead to avoid spikes, and it should work. You couldn't plumb 10 in series though, as uneven temps lead to uneven voltage. I thought up a few rough ways of current monitoring that could add a further led to reduce the power. Nothing great though.
I have found some little led 'barn' type lights.
Available at 30w 50w 80w and 100w, they consist of a linear array, smart chipped cob, placed in a typical barn shaped reflector.
Now I look at these completed units and think a few rivets and some thin alloy sheet... These must suck. But then, these are waterproof units, that won't cook if simply used as they are. But they are crying out for better cooling. If fixed along a cool tube of water, a lot of the heat energy would head that way. The top could be made flat, buy taking the rivets out, and moving the power flex. And assembling with thermal epoxy or plaster instead. You could even fix the lights to a square tube with U bolts. So they can be moved about.
While not entirely water cooled, a lot of the heat would head to the water. But you wouldn't fear turning the water off or down, when you did actually need some heat.
Using 100w variants, you may need just 4 per meter. So that's just two runs of pipe.
Refining the plumbing further, I would use 20mm2 but use two not just one. Put them together like a 20x40 tube with a center wall. To keep plumbing at one end, and the temperature similar at every fitting. As the water goes up one, and down the other.
I'm still looking at the copper pipe and T piece method. Using lots of 10w (or even 3w) cobs, straight off the mains electricity. The 380v I have is a lot of 9-10v leds, so is no small project. But site transformers give 55-0-55 and pc power supplies are a very well regulated 12v and 500w units cost $10. Maybe I should get this hefty 12v and use a number of voltage regulators, for batches of 10v leds. A pack of 10 3w cobs is just £1 and a 3w cob could be just glued to a round copper tube (if I'm feeling lucky)