The thing with copyright, (and I can only talk about here in the UK, but it should be universal), is that copyright is something that is assumed for the creator of the media, and you should not have to claim it. If I create a photographic image I automatically have the Intellectual Property rights to that work, and this is enshrined in law.
The issues arrive when you need to record this so that usage fees and like charges can be recovered, and the lawyers then get involved. The internet has always been considered outside the normal scope of law, as it was in its early days when people would use it to share work freely with others and for free. Now the net has become commercialized, but some of the people who want to earn money from the net are willing to treat the net as it used to be - free for all - but expect others to pay them for "providing" media.
Sorting this out can be difficult and once lawyers get involved, expensive
With the image side of things which is what I am most involved in you can use electronic watermarks (which is not a free service), use tags which may be removed or you can use an image watermark, (and not one at the edge that can be cropped out), or only upload a low resolution Sampler, both of which which ruins the image, for those that want an image for personal use.
All my images that are published online, I retain full rights to but allow their use for non commercial purposes, (including fundraising for Non Profit organisations), I just ask for an attribution).
I always shoot my Images in Raw format, and fully annotate them in the internal metadata - these images are kept as "Digital negatives" and are never directly published, the Geo location and time of creation is also added to the metadata by the camera and my Google timeline will also place me at that location at that time.
I'm not sure what digital tagging is possible for Music files, but maybe a copyright Image inserted into a tag in the MP3 file could dissuade many, as the player would display the image on playback, Also recording the original in a non compressed format and using this to generate the MP3 for upload could be another option, providing a dated master recording . I can remember radio stations , when playing a new released single, would insert a few Station Ident Jingles to spoil any recordings from the radio to tape. with the digital age it's simple to record bit by bit for lossless copying and then edit the file to remove unwanted content so this is not a viable option
