I know it exists and they have shared their methods in the forum.
What they do is:
1- Encode the media of any format: image, audio, source ... etc.
When encoding them, they remain in a unique format, and cannot be read by any multimedia software, even by AGK.
2- Once encoded, it is in an illegible format ...
3- Each time the game is run, you must decode the multimedia content ... progressively (when loading media gradually), or complete (more processing timeout)
When decoding, it requires a timeout for the CPU and Hard Disk processing speed.
4- We load the De-Encoded media, just after loading the De-Encoded media, they are deleted.
The encoded version of the media is always maintained, always for the time of Decoding.