tl;dr The S8/+ only "fast" wireless charges with an OEM Samsung charger. Third-party and knockoff "fast" wireless chargers will experience the "paused" issue. They can work as standard wireless chargers but must be paired with a power adapter that forces it (non Samsung Adaptive Fast Charger and no QC 2.0+ power adapters, etc.) Previous generation Samsungs, such as the S7/Edge and Note7 (R.I.P.), do not have this limitation.
The person in the YT video must have had a knockoff (one good indicator is the hard plastic "lip" on the stand should instead be a rubberized material). I have two knockoffs myself and my results are the same. I also have a third-party Choetech and both of the previous OEM versions; pad and stand. I do not have the new convertible stand.
The long version:
Before I start, please note that I make a clear distinction between a wireless charger and a power adapter. I refer to a wireless charger as the device which contains the inductive coils on which a smartphone rests upon for wireless charging. A power adapter is the device that plugs into a wall outlet and has a USB Type A port to supply the wireless charger with power via a USB cable (typically a USB Type A to micro USB cable). Basic stuff, I realize.
Initial reports from around the web, in particular the above YT video, pointed me in the right direction. According to my own testing and conclusions, the problem isn't the wireless charger or the power adapter but rather a seemingly intentional block placed by Samsung when attempting to use Samsung's "fast" wireless charging method on the new S8/+ with third-party or knockoff "fast" wireless chargers.
As you may know, the "fast" wireless charging method is a non-standard, proprietary Samsung technology, which is said to be compatible with standard Qi wireless charging. I have concluded that, apparently, the new S8/+ can now detect if a "fast" wireless charger is OEM or not. If it is not, you will experience the "paused" behavior when attempting to "fast" wireless charge an S8/+. However, standard wireless charging works fine on the few non-OEM "fast" wireless chargers I tested.
While you cannot select between the "fast" or standard wireless charging method by way of the wireless chargers themselves (or any that I've seen at least), you can force the wireless charging method based on the power adapter you pair the "fast" wireless charger with. Aha!
If you're like most who purchased a third-party "fast" wireless charger to use with a previous generation Samsung Galaxy, you may remember the fun of having to pair it up with the right kind of power adapter that would enable "fast" wireless charging, such as a QC 2.0+ power adapter. Using the "wrong" kind of power adapter should force a "fast" wireless charger to use standard wireless charging and then the S8/+ will no longer experience the "paused" problem. Obviously, this means the S8/+ will wirelessly charge at the standard rate.
I tested and was able to successfully "fast" wirelessly charge my S8+ with an OEM Samsung Fast Wireless Charging Pad (flat, lay down style) model EP-PN920, which is the first iteration of a "fast" wireless charger from Samsung. I was also able to successfully "fast" wirelessly charge with the next iteration wireless charger, the Samsung Fast Wireless Charging Stand (stand up style) model EP-PN930. Both were paired with a basic OEM Samsung Adaptive Fast Charger USB power adapter. I also tested the above wireless chargers paired with an AUKEY Quick Charge 2.0 Wall Charger power adapter model PA-U28 (5V/2.4A) and was able to successfully "fast" wireless charge my S8+ on the OEM Samsung wireless chargers.
I also tested a Choetech Fast Wireless Charger model T518. When paired with a power adapter that enables "fast" wireless charging, I experienced the "paused" behavior on my S8+. When paired with a power adapter that forced standard wireless charging, my S8+ was able to wirelessly charge at the standard rate without issue. This was the same result with two China knockoffs of the OEM stands (one good indicator is the hard plastic "lip" on the stand should instead be a rubberized material).
My reasoning behind this block being seemingly intentionally placed by Samsung seems pretty clear based on the above results. I think the "paused" behavior may not be intentional, however. It could also simply be a mishap with just a certain batch and Samsung may address the issue in the future. Here's to hoping, but don't hold your breath.
Suffice it to say, this is only my experience and yours might be different. Please do feel free to comment on your own experiences. I think it can be helpful to get additional perspective on the topic. Thank you.