Power Point does not allow you to directly embed the YouTube video to your power point presentation slide. To embed videos directly from YouTube, you need to do some work around. First Download and Install YouTube Video Wizard From here . It will add the YouTube video tab under your insert toolbar option.
Video Tutorial:-
You just need to enter the URL of YouTube video and follow the wizard. You can re-size it. One drawback of this is that you need to have internet connection to play the video in presentation.