It looks like your youtube embed code has a few problems. You will probably need to go into html view to fix this. Below is the code I found:
<div align="center">
<object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" width="510" height="350" codebase="https://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,40,0">
<param name="allowFullScreen" value="true" /><param name="allowscriptaccess" value="always" />
<param name="src" value="https://www.youtube.com/v/jaSVUJhDr_A&hl=en_US&fs=1&rel=0&color1=0x5d1719&color2=0xcd311b&border=1" />
<param name="allowfullscreen" value="true" /><embed type="application/x-shockwave-flash" width="510" height="350" src="https://www.youtube.com/v/jaSVUJhDr_A&hl=en_US&fs=1&rel=0&color1=0x5d1719&color2=0xcd311b&border=1" allowscriptaccess="always" allowfullscreen="true">
</embed></object></p>
I think the problem is that the ‘<div align=”center”>’ doesn’t have a corresponding</div>
after the embed code. Also you have a ‘</p>’ at the end of the embed code but you don’t have a ‘<p>’ at the start of the embed. I think it’s no closing the center div that’s causing the problem.
I would modify the last line to be like this: ‘allowfullscreen=”true”></embed></object></div>’
If you’re not creating your own embed codes, it might be a bug in the “Viper’s Video Quicktags” plugin your using. Have you tried using oEmbed, which just allows you to drop in a Youtube URL?