The 250GB SSD is used for Windows 10 Pro, all software and My Documents. My Pictures, My Video, and My Music are all stored on the 1TB SSD. Video production is all done on the 1TB SSD. There are no separate scratch disks or cache disks as I did not find them to provide any additional performance benefit. (I originally went with three 250 GB SSDs, then exchanged two of them for a single 1TB.)
This build rocks at video editing and rendering. Using Cyberlink's PowerDirector 16, it takes just over two minutes to produce a 17 minute mp4 video in HD (1920x1080p) that includes four music clips. For a 3 hour collection of GoPro mp4 files, it took 22 minutes to produce in HD mp4 while utilizing the software's rendering acceleration option.
After running several tests, the primary components for video editing seem to be the GPU and the CPU. With rendering acceleration turned off in the software, all 12 CPU threads would run between 80% and 90% and it would take up to 8 times longer to produce. With rendering acceleration turned on, the CPU threads would run at 35% usage and the GPU at 60% and it would take significantly much less time to produce.
I now believe the 32GBs of RAM is overkill for video editing unless your software specifically requires it. For PowerDirector, my RAM usage never went over 6GBs. I have since installed a VirtualBox virtual machine on this pc and allocated 8GBs to the vmguest. I could probably get away with 16GBs total while running the vm, but I can always allocate more to the guest session. Side not on the vm, video production performance did decline when the vm guest was running, but it returns to super quick when the vm guest is stopped.