The 1905 Steyr-Mannlicher was developed by Ferdinand Mannlicher, one of Europe's most prolific gun designers. It uses the 7.65mm Mannlicher cartridge, which is roughly equivalent to .32 ACP, with a 10-round fixed internal magazine. The 1905 is, in my opinion, a fantastically elegant pistol, handles very well, and has minimal recoil thanks to its light cartridge. The ammunition used in this video is 1940s Argentine surplus (the single largest batch of pistols was sold to the Argentine Navy), which is known for having hard and dud primers (as you will see at the end of the video).
Mechanically, the pistol is a sort-of delayed blowback. It has a spring-loaded cam pushing against the breech that theoretically delays opening, but in practical fact it doesn't have a significant impact. You can see how quickly the breech opens in the video...