RTX4080 with it's 16gig of VRAM would be a nice upgrade, but rtx3070 is also very nice and well suited to Vegas, except the 8GB of Vram, although even that depends on how complex your projects are.

As I've been without a computer for some time, I made videos for a channel in 1080p, the time varied, but I think the file was close to 1 Gb on Youtube. For a 10 minute, 4K video, would it be nice to have a 16Gb GPU? For example, today a 4070 Ti costs much more than a 3080. The VRam difference is 4 Gb. Is there a big difference in performance in a rendering process?

I see for some work Vegas is using more than 10GB of my 10GBVram, and I wonder about the performance implications related to that. Vegas doesn't have the problem of other editors where it simply won't work or it turns the GPU decoder off (that I"ve seen) so it's less important.

The 4070ti with it's 12GB Vram seems ok, but possibly not as an upgrade from a 3070. See what others have to say

It draws too much power for an air cooler. Look at the i5 or i7 instead. I have an overclocked 13600K in a good airflow case an am very happy with the performance. See my signature for details and benchmarks.

If you're doing AI effects, HDR, etc. more GPU ram is nice to have. I'm getting by with 4 and 8gb just fine for 8bit 4K AVC editing.

14 different air coolers. tested on 13900k

That testing must have taken forever to do! The video states the CPU can draw 330W but he recommends 253W or less to maintain clocks and all tests were just 10 min. Conclusion around 38 min. was "an AIO is a must" for a CPU drawing over 200W.

I don't see why you'd pay a premium for a 13900K and then limit the wattage significantly. I've run my i5 with cores between 5.1 and 5.5 GHz at 100% for 10 hours straight drawing 200W doing AI calculations on my machine (not on a test bench- with the case on) Higher than 200W sustained and I thermally throttle even on the i5-13600K in a cool room with a high airflow case.

We have aktual reports that the nvidia 4000 serie makes problems in Vegas. Please be aware of those issues, to disable the nvidia card to be able to work with Vegas is not so great. I have no idea if and when this may be solved.
 

https://www.vegascreativesoftware.info/us/forum/gl-transitions-always-crash-program-solved--140272/

14 different air coolers. tested on 13900k

Something not right there with the Noctua NH D-15. I have one on my 9900k and it came with 2 identical 140mm fans. Looks like he's got a 120 in the middle. Also, my fans are mounted the other way... the outside is not mounted over the ram. One thing about the D15, however, is that the fans clip onto the radiator fins and can be aligned or mounted any way you want. So I could buy a 3rd identical 140mm or smaller 120mm fan and add it over the ram, depending on how tall the ram stands. Looks like he's got the 140 over the ram and mounted pretty high which might limit airflow through the radiator and come pretty close to hitting the top of a typical case.

Btw, with the d15, I can only get 4.8ghz on my 9900k (not overclocked) running prime95 small ffts overnight... it's actually rated for 5ghz. Although I use both, I prefer p95 over Cinebench for system validation, stress testing, and burn-in. It not only stresses the cpu, ram, power supply, and busses to their limits, but informs you if doing that causes anything in your system to generate computational errors requiring bios adjustment. I haven't bothered adding a 3rd fan because Vegas doesn't push the cpu that hard with a good gpu doing the heavy lifting. And I have a small clamp-on ram-fan there instead. But I did go with a single radiator aio on my 11900k. Most folks recommend a dual radiator aio minimum for the 13900k which runs a bit hotter than previous gens. The nice thing about an aio is it's much lower in mass than an air cooler and won't physically stress the cpu socket or risk cracking the motherboard if you move or transport your system without dismounting it first. But it might be a problem if you ship it in an unheated truck in the winter.