Embedded video from website not working

I have tried to add a website video to storyline 2 without success.  Added the embed code but the error message says embed code cannot be added.  It was a successful add in Microsoft Publisher, why not Storyline? (embed code below)

<iframe width="560" height="315" src="https://www.youtube.com/embed/t2SB6JtgPhM" frameborder="0" allowfullscreen></iframe>