Software :: Adding A Watermark To A Video?

If I were to use SnapzPro to capture video of my screen (this is not DV related), what software could I use to add a very simple, slightly transparent watermark image to every frame of the video? Really, the fact that I'm using SnapzPro doesn't matter, but I mention it to say that I am not working with digital video that I shot with a camera, just video screen captures.

Also, what software could I use to add a simple, static image to both the beginning and end of the video. This would be something like a title screen that starts and ends the movie, and lasts about three seconds.

I'm not looking for professional software, and prefer to avoid it, in fact. I just want something to get both of these seemingly simple tasks done. Something free would be great. If I have to use two pieces of software, one for each task, that's fine, too. I just want to know people's thoughts so I get something worth using.