I think it is possible to embed invisible information into videos and images. This way peopple could track where you got an image from, the source from which you copied it, and people who copy your image to share it again. https://github.com/ShieldMnt/invisible-watermark

Services like youtube or twitter could embed such watermarks into content they serve to specific users without them knowing; Smartphone-cameras could mark images in secret.

I guess blurring, rotating or dithering the image could destroy watermarks. Or maybe just sharing a screenshot of an image instead of the original image. Format conversions may help too.

Keywords: digital-watermarking. tracking.