Part 2 In the Build Series 
You may want to mention using shielded paired cable for connecting home/limit switches, grounding the shields at the tinyG end. Some folks, particularly those running Heavy duty (noisy) spindles have experienced noise triggering limit switches. Similarly, I think using separate power cords for spindle power and stepper/tinyG power is always a good idea, noise conduction across power supplies can also be an issue.
I would also suggest you provide folks with the tinyG wiki URL. After watching your videos, the wiki will make a lot more sense, and re-watching the videos after reviewing the wiki should help there as well.
Thats good information. I offer links to the wiki in each video. Its impossible to cover every single detail. The goal for these videos is to make it way easier to get set up amd running on an OX CNC with a tinyG. I do show them that i am running NC switches in a later video. I think I mentioned noise prevention is a benifit of NC switches.
The AC in just means that you can use a transformer to get your 48V and don’t need to use a regulated DC supply. AC doesn’t imply 120 VAC. It still means 48VAC.
The PWM wires from the TinyG to the Spindle Controller don’t carry any current, and can be considerably smaller than what you’ve used (just an FYI). There isn’t any problems with using larger wires either.
If you twist the + and - wires together, it helps to reduce electrical noise. So I always twist + and - to/from power supplies and the/from motors. Brushed motors are especially noisy.