This extension is used in conjunction with the Adaptive screen saver (on Linux) and its purpose is to detect if a HTML5 video element is playing video. If such activity is detected, it will be passed along to the Adaptive screen saver which will be listening on local port 4444.
No details about the name or content of the video is recorded; it only communicates something is active and forces the Adaptive screen saver to reset the session's idle time.
The Adaptive screen saver can be downloaded here:
https://big-endian.nl/download/screensaver.adaptive/
