Easy Web Gallery Builder EWGB can add watermarks to images and create video galleriees and thumbnails directly from video files. I think it is not supporting adding watermark to video files, but I am sure such option will be added in the upcomming releases
Watermark Master is good! i also find SDK for Watermark Master engine, and created sript for batch video watermarking Very nice!
Take a look at watermark factory - but its not free. It can batch water mark videos, add images, add text, change the video size, change the output video type, font color, font location - just about everything you need. http://www.watermarkfactory.com/ I have been using it for over a year, maybe 14 - 16 months with no problems. On two occasions I reinstalled my operating system and lost my software key. I sent the company an email with my details and a few hours later they emailed my key to me. The company has two products, one for videos and one for pictures. I have only used the video watermark program. About a month ago I stopped watermarking the entire length of my videos, it seems less professional. For just adding text, or basic editing I use windows movie maker that came with windows XP.
Yes, Watermark Master Pro is best. You can also use Moyea FLV Editor for cutting and watermarking your FLV videos.