Chiming in because I know a little bit about this.
1st guy TechDeals is pretty good. I haven't watched this video but I'm going to guess what he says and why it matters.
There are 2 factors when looking at SSDs. Price vs Performance and SSD design.
1) Back when SSDs were much cheaper, like Sep-Nov 2019 1TB NVME SSDs sold for ~$100. While 512GB were ~$60-70.
2TB NVME SSDs could be had for $200-220 with the Intel 660p sometimes going on sale for ~$180
1TB was really the sweet spot for NVME SSDs for price.
2) 1TB also happens to be the sweet spot for performance. Anything less, and you're not getting the most out of it.
See, an SSD has dyes and NAND packages where data is stored. Think of it like a buckets of water. On the logic board (PCB) of an SSD, the controller sends out data and fills these buckets of water.
As a cost saving measure the logic board, regardless of capacity, uses the same design. So on a 1TB if there are 8 routes or methods to fill these buckets and 4 NAND packages it's a fully saturated process.
But what happens if there's only 2 NAND packages (a 512GB SSD). Then you have only 4 routes available (but the other 4 are on the PCB). So if you have 100Mb to sent to the SSD it can only take 4 streets instead of 8. It's a bit slower. And this happens at lower capacities.
2nd video, did the guy use a Mac? I've used a Sabrent Rocket to Time Machine clone and replace a Macbook Air's SSD. No problems. Maybe what he's saying is a common problem in Windows based machines. The Acronis cloning program isn't as good as Samsung's Wizard, or whatever it's called.