I think everyone should watermark their videos when editing, the in video programming ones aren't really watermarks as they are placed on top of the video like an overlay (similar to an annotation) so they are not a defence against someone stealing your videos. Having them hardcoded into your video means removing them will be tough for most people. We use a watermark in almost all of YTtalkTV's videos, if they were stolen its clear to others where they originated from. I would watermark them whether you're on camera or not.
I just use a full opacity PNG image of our site logo and drop its opacity when placed on a new track in Vegas, saving them at say 50% in Photoshop could be easier for most people and quicker but sometimes I find I need to adjust it so it becomes more visible.