Many presenters present from their own laptop computer through a projector. When our animated templates, or other presentations which contain video files, are presented in this way, some laptop users may encounter an issue with the video not appearing on the presentation screen. Typically this will look like a black box in place of where you expected the video to be.
This is due to limitations of the video cards in some laptop computers. The newer the computer, the less likely you are to encounter this problem.
If you do encounter this problem, you can tell your laptop to display the presentation on only the projector, by toggling to use only the external video port on your laptop. This is typically done by holding down the Function key (Fn) and the pressing the monitors key (a key with single or double rectangles on it). The projector will then show the video files.
There are a few other options. Here is a link to PPTFaq.com, an excellent PowerPoint troubleshooting resource, with several more ideas on how to resolve this issue.