I didn't comment much on the power supply because honestly, I don't think it's so big of an issue.
Yes, it's a "budget" psu, with not so great components, but at the same time it's not going to be heavily used, so it's gonna last a long time anyway.
For example, while he's editing the videos in Vegas, basically just the cpu will be used a bit, so the power consumption will probably idle at around 50-80 watts. When he's rendering for a few hours, maybe the system's gonna use 2-300 watts.
So basically the power supply will barely warm up at those 50-100w of power consumption (10-20% out of those 650w) during most of the time it runs, and then it will "sweat" a little for a few hours every 2-3 days or so, when a video is actually rendered.
Could you do better? Yeah. It would only take maybe 10-20$ more, to go with a Gold efficiency psu from a good brand ( Seasonic, EVGA, Corsair etc) but if the use of the computer is like I say above, it really won't make much of a difference.
I agree with what others say about the platform though. x299 is not a great choice. It's practically already outdated, whatever Intel's gonna release is probably going to require new chipsets, so not much upgrade choices other than what's now... you'll find cpus on eBay.
Then all the exploits for Intel and the ton of Windows updates to fix various exploits in Intel cpus, and patching some of those exploits requires microcode updates, which must be performed by updating the bios - and if that motherboard is on the cheaper end of x299 boards the board maker may be slow at releasing bios updates...
Ryzen processors and the Zen cores don't suffer from so many exploits as the Intel cpus and whatever was found to be vulnerable was fixed through simpler Windows updates, without much stress. With AM4 socket from AMD you'd also have future upgrade choices
Right now I also have to agree with everyone, this x299 board with that cpu is like pairing a Threadripper motherboard with a 8 core 1900x, a shame... the 1900x is available as a choice in case user needs lots of memory (8 slots) or lots of pci-e slots (since cpu has 64 lanes if i remember correctly)