i know right here is one fix if u got 2010 powerpoint youtube did some changes thats not compatable with it . 1 way around it that might work for you is within the use old embeded code were it says version=3 change it # into 2 insted of 3. do this in both appeareances.
example <object width="1280" height="720"><param name="movie" value="http://www.youtube.com/v/1rcqwRgVvvw?version=3&hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/1rcqwRgVvvw?version=3&hl=en_US" type="application/x-shockwave-flash" width="1280" height="720" allowscriptaccess="always" allowfullscreen="true"></embed></object>
change the #3 to the #2 thats it. then paste it in your powerpoint insert video from web.
For Powerpoint 2013 you need to download a youtube downloader with a converter. i recomend YTD video downloader by Greentree Apps. with this you copy the url from yt for the video u want to copy to powerpoint. open the YTD and place the url in the DLvideo box. after you DL the video convert the file to wmv format and save it your desktop or somewhere on your computer where u can find it. so when you open powerpoint you insert video from your pc and not the web. This is the only way you can play video from youtube in powerpoint 2013 becase its new software and youtube and adobe have yet to upgrade their software to be compatable with the new pp2013. I know this now because i had the same issues and got this solution from a micosoft powerpoint tech. and now i have no problems with youtube videos and powerpoint.
Please let me know if this was right on the money for you.