A chain passing over and out of round sprocket will be tight as it passes the highest spot.
A chain running over a sprocket that is loose, or has thick and thin spots, which would cause excessive run-out, will not cause tight links, but it will be at risk of throwing the chain off.
The high tooth or teeth, or tooth or teeth with excessive run-out do not tatget individual links.
If you have that much of an issue it should be immediately noticeable, as it would be excessive.
You will find that a non o-ring chain gets lots of tight links, as there is nothing to keep dirt and moisture out of the inner pins.
On an o-ring chain, tight links commonly have broken o-rings, so dirt and moisture has gotten in.
If not, clean and lube the chain and the tight links can be fixed.
If not, the chain is worn out.
Chain stretch is when the pins wear inside, and the chain itself IS actually longer, this is not as common with newer chain technology/stronger materials.
Do chains need adjusted as sprocket teeth wear? Yes, and the outer chain pins are wearing also, so there is more slack.
These are parts that wear out.
If you keep the chain clean and adjusted correctly(steel or aluminum rear sprocket), then you will not have problems for 20k-30k+ miles.
Also, if you have an aluminum rear wheel in good shape, with minumum run-out, or a spoked wheel, with all the spokes adjusted and the wheel trued/minimum run-out, so either wheel is straight.
And, the axle is even in the swingarm(with good wheel bearings) then that wheel will spin in the swingarm with minimum run-out.
Now, put on a bent, thick and thin with maximum run-out, or out of round sprocket(s) and watch them wobble.
The chain will 'pop' as the pins pass over misaligned teeth, and the chain may slip or jump off...but unless it pulls the axle out of alignment, which it cannot, assuming the axle adjustmenf is correct and cannot move...then the wheel is going to still spin true, with minimum run-out...the chain and sprockets cannot effect tire wear...with one exception.
If the chain is too tight, then it limits the travel of the rear shock, which will cause the rear suspension to be too stiff, and bounce about, causing poor tire wear.
But, if the chain is adjusted Correctly, then the suspension travels Correctly, and the sprockets or tight chains links have no othet effect on the tire.
Not everyone on youtube is correct.
You can spot a tight chain link from 20' away with good eyesight, and the chain in the video was straight through it's entire rotation.
