I think I found a solution to this issue that may work for everyone.
When you are ready to "build" your new video,
notice that when you click on teh "build" icon and the "Video Output Setup" appears, within the "Windows PC" tab, we are limited to our output formats (offers MPG, AVI, WMV, ASF only). I looked on YouTube's site for preferred video format (to upload), and it says MPEG3 or MPEG4.
So within the "Video Output Setup" window, I looked under the "Mac" tab (as opposed to Windows PC); There, they offer MP4 format (which I assume is the same as MPEG4). I quickly created a short trial video, 11.5 seconds long, through the MAC tab with MP4 format, then uploaded it...
Played it back from the remote video host, and this time, it played back video at proper speed. This solution worked on both Youtube and Shutterfly.
So try that out, should work....
works fine, and best thing is the video is now only 19 MB (as opposed to 115 MB in MPG format).