First, in normal view, click the movie you want to play in Full-screen mode.
Second, under Movie Tools, on the Options tab, in the Movie Options group, click Full Screen playback.
How to preview a movie:
1, click the movie, and then under Movie Tools, on the Options tab, in the Play group, click Preview.
2, click the slide with the movie, and then click Slide Show or press F5 at the bottom of the Microsoft officepowerpoint 2007 window. If you set the movie to play when clicked, click the Movie box.