All I hear is this goes over his budget and it is driving me crazy! I think he should extend his budget to around 1500. I would definitely Extend my budget because you will be more happy wih the i9
One more thing: Video editing will run better on an intel cpu (just throwin' that out there
You're forgetting a couple of important things here. The first being, not everybody has that kinda cash or the ability to just up a budget by 500 bucks. The second being, 6 cores and 12 threads will be more than plenty considering the Nvidia GPU I put on the list will do a better job with helping render times than Quicksync; at better quality too. I have an 8 core Ryzen 3700x and I regularly edit my videos on a 45W 6 core Xeon processor in my laptop with no problems. The 3600 will be faster than even that due to having more wattage to work with. Following up my second point, the third is this dude is rocking a 2010 Macbook Pro which uses a Core 2 Duo. A dual-core processor from 2006. Anything made in the current generation, even a 120 dollar Ryzen 3300x is going to run circles around what he has now and he'll be completely happy and capable of handling his workloads with the new machine. Considering he's been using this machine for god knows how long, I'm sure it won't matter in the long run. So that being said, restraining to his budget will not only make him happy in that department but also happy with the new machine he will be putting together to be able to properly handle all his current work loads.
Rule number 1 of helping people with builds in Techist; consider the user above all. If he's been using an olllld Macbook for 10 years or so and says he has only 1000 to work with, there's probably a good reason. This isn't a situation where somebody is saying they have 500 and want to max all games and stream at the same time. I'd say in that situation to save longer or you'll be disappointed. What if they're disabled and have little to work with on a fixed income or this is charity work of some sort? We don't know. Is spending 500 extra worth the few extra minutes saved on render times going with an 8 core? No, not in this case.
And you'd be right, because it's an old quad-core Nehalem based system with slow DDR3. Take that a step further and compare that to a power limited dual core Core 2 Duo from 2006. Going to a Kaby Lake level performance 6 core/12 thread with DDR4 is a massive jump and would be even with your dad's 09 Mac. The old 1366 CPUs are really starting to show their age these days, and even my Sandy Bridge based 3960x would be a good leap above your dad's 09 Mac for productivity tasks (albeit minus Mac only software).
I guess one way to put it is, 3 years ago I had my 7800x that I used as a daily driver and today it's still capable and ever so slightly outpaces my 3700x (in gaming) at 5Ghz as a 6 core CPU. Anybody going from either of those old machines to a modern 3600 would be a night and day difference. Another thing to think about, is neither your dad's 09 Mac nor OPs old Macbook has AVX2 which helps greatly in production applications today, and why I'm perfectly ok editing 4k video with my laptop that has a Xeon E-2186M paired with a Quadro P2000. The slight rendering time difference between it and my main rig isn't justified hogging up my 3700x when I could be gaming on it instead. Likewise in this situation, the extra cost isn't justified in trying to squeeze 8 cores in.