Slideshow Video doesn't play in iPhoto 9.5 and Mavericks 10.9

I have just upgraded to iPhoto 9.5 and Mavericks 10.9

(from Snow Leopard, and iPhoto '09).

I am trying to do an iPhoto Slideshow.

I chose one of the themes, pick a music, and start "Preview".

When the slideshow gets to a video clip, the screen goes black, while the music continues to play.

In my old setup, I was able to see the video clips in the slideshow during "preview" or "play".

Any advice? Thank you!

I am trying to organize holiday photos/videos into slideshows that can be easily viewed by family.