> DRM can mean "book is imprinted with the purchaser's name & cc #.
So here comes the watermarking can of worms
The idea here is that if a bootleg file is found on the darknet, some sort of penalty can be excercised against the person who's ID is found in the watermark.
The first weak spot here is that the only way removal of the watermark can be prevented - is based on crypto. All the arguments that apply to "copy protection variety of DRM" also apply here. A pirate who could remove the DRM prior to upload to darknet, could also remove the watermark. No principal difference.
The second weak spot is that the pirate could choose not to remove the watermark, but to -alter- it. A pirate who knows how to form a valid watermark ID for Steve Jordan, could plant that watermark on a file and -then- upload it to the darknet.
Or an angry spouse could take a watermarked file and upload. Or someone's laptop could be stolen. Or a mobile phone.
Basically, by legally buying a watermarked file (and failing to remove said watermark), the customer exposes himself to danger of being at receiving end of whatever penalty is supposed to happen to the pirates.
The actual uploading pirates of course would never be caught with this - removal of watermark is principally no different from removal of copy protection.
However, in addition to "normal pirates" you would have "griefer pirates" with sole purpose to cause harm to some watermark owner.
Conclusion:
* For prevention of piracy - still useless, if not worse.
* For being user friendly - yes, it lacks all the problems of "copy protection". At the cost of exposing customers to being framed as pirates.
The second weakness could be ignored, sort of, if the assumption is that the customer is responsible for always protecting the content with crypto himself. The first weakness - no go.