You have to make the powerpoint a YouTube video first. Coz YouTube is a video hosting site, and it does not support a non-media format like PPT, PPS, PPTX.
To make a YouTube video from your powerpoint, take such easy converters as Moyea PPT to Video Converter to convert to MP4, etc, free trial at
http://www.dvd-ppt-slideshow.com/ppt-to-…
Next, upload the PowerPoint video to YouTube with your account. It will play smooth like a video when you click the Playback button.
For more about the issue, see this post at
http://www.dvd-ppt-slideshow.com/blog/yo…
Hope it helps you out!