This video shows a small amount of firearms supposedly used by Russian Special Forces. They start right off with the folding machine gun PP-90.
This appears to be a MP-443 “Grach” pistol.
Stechkin Automatic Pistol (APS)
Below is a modified variant optimized for suppression. It is called the APB. Click here for more info.
Below is the PSS.
The PSS uses a specially developed 7.62×42mm necked round SP-4 (СП-4), the same as used for the OTs-38 Stechkin silent revolver. The cartridge contains an internal piston and a propelling charge, with the stem of the piston against the base of the bullet. On firing, the piston delivers enough impulse to project the bullet from the barrel to an effective range of 25 meters. The piston then seals the cartridge neck, preventing noise, smoke, or blast from escaping the barrel
The SMG is the PP-91 KEDR
Not a bad selection of guns in such a short video. A big shout out to Hrachya H. for helping me ID these guns.