The video is only 2:40, but if that's really tl;dw the Tesla AT&T is about 3x faster than Verizon and 9x slower than T-Mobile (for downloads, which is what matters). In that one specific location.
So if you live exactly where MelGeek lives (and never drive out of that cell) that's the speed you can expect. It's interesting enough to me that I watched the whole video, so apparently I'm glad MelGeek did the test (thanks!). But if you want to know how YMMV (Your Megabits May Vary), you'd have to make multiple measurements across the country at various times of day/week, in various weather conditions. So the test is of limited use for any given person's situation. Same as any test of cellular data rates, really.