Wouldn't using something like FRAPS or Raptrs screenshot overlay keep the watermark from showing up? If the watermark is shown all the time then that would be some sort of overlay, which is very easy to bypass as well. Worse case scenario, alter the contrast or color depth on the image and watermark goes away pretty easy. I was going to purchase watermark tools for my 3D art until I discovered that they don't actually promise something from being distributed or altered, but rather watermarks are only good for keeping items pristine to prove ownership or that something was unedited. Editing a watermarked image can easily destroy the watermark at least that has been my experience when testing out various watermark methods.
Xbox Live Ambassador (RET) Founder of PERS0NA, a non-profit scientific paranormal investigation society "American by Birth, Gamer by the Grace of God"