Valve has introduced a new set of features in Steam. It has added tools to the beta version of the Steam client that allow you to record gameplay.
Video recording can be done in the background or on-demand. The recorded clips can then be edited, for example, by cutting out the desired fragments and adding timestamps with particularly interesting moments on the timeline. Some games are capable of controlling the video timeline themselves, marking the seconds with important events such as boss fights. Currently, this feature is available only in Dota 2 and Counter-Strike 2, but Valve has already provided other developers with tools to work with video, so this capability will soon be seen in other games as well.
Video recording is supported on Steam Deck, so owners of the portable PC can also make clips. It also works in any games where the Steam overlay is opened.
You can share the finished videos in Steam chats and send them to other devices.