Valve has released Steam Game Recording as a new feature for the Steam store and client.

Game recordings are saved as MP4 videos, and they can be shared with temporary links with QR codes.

Dota 2 and Counter-Strike 2 are the first games with timeline marker support.

Saving a game recording in Steam.

Valve

you might try out Game Recording by opening the Steam client and navigating to parameters > Game Recording.

Source:Steam News,Steam