With today software, Watermarks and embedded items can be removed easy. Signature are ignore as most are students who only have account for a short time who download the photos they want on line. Anyone can download from free WI-FI zones.
Even with Flickr having copyrighted noted on the site, people will use any photo to promote their site, product or what every that they can get their hands on from that site including my photos.
Because sites are off shore, its hard to deal on a legal base as well costly.
I have sent noticed to various places that have used my photos illegally and they have either pay me for the use of the photo or taken them down.
One big problem that is tied to various members of the board is how cheap they sell their photos to developers or others. I am not in the business of selling or asking money for my photos, but when asked, I don't expect to asked high price for it in the first place. Some prices I have been offer are an insult because they know someone here will take it. Many places have free use of my photos who have asked for permission to use it in the first place. This includes architects, developers, cities and the list goes on.
Because of illegal use of my photos, I have cut back on posting on this board as well Flickr of photos I shoot. If I got $.005 for every hit I got on my photos, I would be raking in some big bucks these days to the point wouldn't have to work at all.
Youtube has a policy that can get videos removed very quickly. I have a number of videos block in various country because of the musics that is on my video that I had not control over when recording events live like a parade.