http://www.sitepoint.com/article/watermark-images-php That might help you out. I know it's not for videos exactly, but it might give you some ideas.
Do you need the script to watermark your videos automatically? If yu are prepared to do it manually, there is a batch function in Camtasia (if you have it) where you can select multiple videos to watermark. Then set it off and go for a long walk.
The way i would do it is use a flash player and put a layer in front of it with you logo on it makes it simple but wont be there when they download it.
download a flash video player then edit it and on top of the video file just create a layer with ur logo
Hi thanks, I am newbie here..... so where to download the flash video player (may be I have one in my computer, but just dont' know which one?) and how to "edit it and on top of the video file just create a layer with ur logo" Sorry for newbie question, but I really don't know how to do that.... thanks in advance
Yes, layer to create not simple, besides, this layer can be removed from video very very simple . Therefore use VideoCharge for watermarking video! But! even from video watermarks can be simply removed (for example, applay CROP filter), So I advise to read http://www.videocharge.com/articles.php?id=8