If you are interested in showing a just a portion of a video clip from YouTube linked from within your PPT presentation, you can create a link with a customized start-time. To generate a customized link, follow 3 simple steps:
1.) Click the 'share' icon located directly below the video.
2.) Check the 'start at' box and fill in your desired start time.
3.) A customized link has now been created. Copy and paste this new link into your PPT.
For more information on how to show a video within your PPT presentation, see our document on Using Video in Powerpoint.