To be fair, the issues seen in the video were almost certainly from using subsonic rounds in a blow back operated gun, not an issue with the gun itself. Even in a factory built gun, subsonic rounds often don't have enough oomph to cycle the slide on their own. Sometimes they might but you should be expecting to have to manually cycle the slide if you're using subsonic rounds in a stock blowback operated gun.

The only real fix is to swap out the recoil spring for a lighter one (which can cause other issues) and/or use subsonic rounds that are specifically designed for your exact model of gun (if even available). There are technically other things that can be done but for those you're looking at gunsmith levels of work.

That print probably works perfectly fine with normal ammo.

Subsonic rounds and a supressor are exactly the type of things this maker is talking about.