A PDF is the popular file format developed by Adobe, designed to present text, graphics and other elements in the exact format as they were laid out by the page designer. While you can not import a page from a PDF into iMovie directly, the Mac OS X built-in screen grab utility can capture an image of the PDF that can be imported into your iMovie project like any other picture or graphic.
Double-click on the PDF to open it. Scroll to the page you want to add to your iMovie project.
Press the "Command" plus the "Shift" and the "4" keys simultaneously to launch the screen capture utility. The cursor will change to cross hairs. Click at the upper left corner of the PDF then drag it downward and to the right to encompass and capture the full PDF. Release the mouse to snap the shot. The shot of the PDF will be placed on your desktop as "Picture X."
Click the iMovie icon in your dock to open a new iMovie project or open the iMovie file you want to insert the PDF into.
Drag the icon of the "Picture" which was copied to your desktop to the iMovie Project Library.