Unfortunately, it's often necessary to watermark an uploaded video to deter unauthorized use. I can see where some people might be offended at having a name or logo staring at them through a production. Are there any conventions or rules of etiquette associated with watermarking?

If you are going to watermark your videos keep it discreet, in the corners or center bottom. Look at your local TV stations for guidance. In my opinion if you don't want your videos used don't put them online.

In my opinion if you don't want your videos used don't put them online.

Agree with Nicholas on watermarking size and location. Also agree with his statement above. If you use one of the popular video hosting sites like YouTube or Vimeo, you're surrendering virtually all of your rights to your piece.