When the video player requests a video file, a temporary URL to that file (such as a HLS .m3u8) is generated by the system. That file includes a secure token.
The advantage of this is that that token can also be used to determine whether that URL has expired. This helps prevent your users trying to link directly to your files (hotlinking) since the video file’s URL automatically stops working after a period of time.
All of our professional video hosting packages include this ability as standard.