If you found this code in a chat or a forum, it is likely intended to be appended to a specific domain (e.g., ://discordapp.com... ) or entered into a specific search bot to retrieve the video.
Part of a URL for a Content Delivery Network where a user has uploaded a private or semi-private video. Hcstxbg4us S1mOxM16wQ mp4
Unique strings used by databases to locate a specific .mp4 file. If you found this code in a chat