In error, a close parenthesis character has been visible as a stray character in the YouTube embed code at least all day Tuesday, March 11, 2014 and part of the day Wednesday, March 12, 2014.
There should be no parenthesis character after the closing "greater than" character
<iframe width="300" height="169" src="//www.youtube.com/embed/-YCeIgt7hMs" frameborder="0" allowfullscreen></iframe>)
Notice the parenthesis at the lower right of the video ...
It is easy to fix. Just remove the parenthesis manually from the code.