Wow, you really went above and beyond! I would have explained my choices more if I had anticipated someone grabbing the ball and running for a touchdown.
I can see how the way I used the PCPartPicker build page - including multiple potential choices for a single component like monitors and internal drives - can trip someone up. The $4100 system total is actually about $2100 when I winnow those choices to my ultimate picks so your spec is actually $1000 more than I'm planning to spend. I've taken advice on some of the crucial components from vendor forums/specs of the cameras and video editing software that I'm using that those components are adequate to the intended use.
To address your specific recommendations:
1,2: The i7-4790K is capable for the task and won't be OC'ed so the Hyper 212 should be okay.
3: You're right about not needing 32GB and I've removed that from the build list.
4: One big SSD costs more than the 3 smaller ones, or 2 if I don't go with the third. Also, being cautiously conservative, the SSDs have a maximum write limit even though that limit is big. The scratch drive will have lots of reads and writes over time as I copy/edit/remove video files so I'd like to be able to replace it without consequences to the system if the need arises. It also SEEMS like there would be speed advantages connecting multiple drives to multiple SATA III MOBO connectors over one drive to one connector but maybe I'm wrong.
5: If the WD 4TB 5900RPM you suggest has better reliability (big issue) and price/performance than the 7200RPM drives I've looked at then I might go that way since speed isn't the biggest issue with how I'll use the internal HD.
6. The WD 5TB plus enclosure is kind of pricey but I'll look at it.
7,10: A single 27"/28" 4K display driven by the 960 is "better" in this case because it meets the need without the cost and real estate requirements of the multi-monitor setup.
8. Yep, if I hadn't already bought a tier 2 PSU based on Tom's list, yours would have been a better/cheaper tier 2 choice.
9: You're probably right about Win7. I needed the XP compatibility in my current Win7Pro system, which I'm keeping, but that isn't true of this new dedicated editing system.
Thanks for your efforts. I'll look at those drives.