Answers for a couple follow up questions.
Here is a link to the actual mount I used.
https://www.amazon.com/gp/product/B000WYVBR0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
I went with a pair of the $25 mounts mostly for the 20" arms. Longer arms give you more room to move the hood around. I built my own led light and its pretty heavy, so the additional weight capacity of a pair rated 88 pounds was appealing. I think you could use a single mount for a bigger TV, but ironically two small ones is still cheaper than one big one.
The remaining piece of the wall mount is 1 5/8" wide. So I made my mount 1 3/4" inside width to fit around the wall mount. When a couple of washers are added, it fits together well.
I use 1/4" thick wall aluminum, but only because I had it on hand. You can get aluminum channel that is 2" wide outside dimensions that is 1/8" thick and should be 1 3/4" inside dimensions for pretty cheap. You can also get channel iron for a little less money, but at the expense of weight and rust corrosion.
One thing to consider is the strength of the hood itself. Wood probably isn't strong enough to keep its shape if it is only supported on one side. I didn't cover it in the video, but there is a pair of 1/4" x 3" aluminum flat bars bent at a 90 that actually helps keep my hood in shape. Admittedly my hood is pretty flimsy with all the cuts I made and 1/4" plywood for the shaker door look. My hood is mounted by sandwiching a pair of aluminum brackets together that is also held up with a bracing wire. So there is almost no load at all on the wooden portion. The hope is that will keep it from warping or bending over time. If you look at the video again, you can see there is a black "strap" on the inside of the hood. That is the powder coated aluminum flat bar. My led heat sink is actually mounted directly to that and not the wood.
