I want to add simple title with black background while video is playing. All I've found that you can create title like a simple clip, and then use it in the beginning or the end... is that it =(? When you placing simple title over video, background becomes transparent, and I want it to become black.
It depends on the style of title you use. Only a couple of styles give the option to alter the background color. These styles are the following:
You can find Apple's documentation here: iMovie '11: Edit the text and appearance of a title