1. Open your project from Powerpoint.
2. Click on View>Toolbars> Control Toolbox>More Controls. goto "Shockwave Flash Object."
3. design a box size required. Right click on the box and choose "Properties." Double click to open "Custom."
4. Copy the link that from YouTube video (i.e the embeded code not the addrress from address bar) and paste it in the URL box under "Custom."now change the settings according your requirements.
5. Delete the "watch?" and replace the equal sign with a forward slash.
   Make sure the "embed movie" box is unchecked. Click "Apply" and "OK."
6. Save your presentation. Open it and make sure the video is working properly.

thats it!