Try this video tool, import your video first, then add text/image watermark for every frame of yur video. Step by Step Tutorial: http://www.flash-video-soft.com/blog/?p=196 I hope this may help you
You can use Moyea web player (http://www.playerdiy.com/ ), with which you can add image watermark, HTML watermark, text watermark or video watermark to your video. Moreover, you can also make flash video player for website with it.
You can also do all this very simple and quick online. Go to Bubbleply.com. But there are more sites like that. Kicklight.com is also interesting. Have a look... You'll get new ideas.