Depends on the sophistication of the watermarking. Watermarks embedded in the media itself (audio or images) can often be more robust than the information in th

Depends on the sophistication of the watermarking. Watermarks embedded in the media itself (audio or images) can often be more robust than the information in the media itself (i.e. even if you blur it so as to be unreadable the watermark can be extracted). It basically boils down to encoding a very small amount of data in the media as robustly as possible, and modern signal processing is very good at that.