And then of course....you could just say you watermarked it...without actually doing anything at all. That's a LOT less work and might scare of most leakers just the same
You could even post occasionally that you banned "user X" for having leaked your stuff, clearly proven via your fancy watermarking...with "user X" of course never having existed at all. In the end you have to decide whether you want to spend time on such nonsense (it can always be circumvented anyway!) or decide to just not care and rather work on actual content.