If you want to embed a YouTube video from a given time in WordPress, you can just add the following phrase:
#t=XmYYs
For example,
http://www.youtube.com/watch?v=e5cfyAt-0rU#t=3m12s
If the above method does not work, please try to add the string "?start=X" (where X indicates the number of seconds.)
For example,
<iframe width="420" height="315" src="//www.youtube.com/embed/e5cfyAt-0rU?start=192" frameborder="0" allowfullscreen></iframe>