<iframe width="100%" height="100%" src="//www.youtube.com/embed/qUJYqhKZrwA?autoplay=1&showinfo=0&controls=0" frameborder="0" allowfullscreen>
If you remove ?autoplay=1 the video does not work. Looks like you cannot use the controls parameter without autoplay enabled.
Not sure why this is not mentioned in the YouTube embed writeup.
Hope I'm wrong.
https://developers.google.com/youtube/player_parameters#controls
Set autoplay=0
<iframe width="100%" height="100%" src="//www.youtube.com/embed/qUJYqhKZrwA?autoplay=0&showinfo=0&controls=0" frameborder="0" allowfullscreen>
As seen here: Autoplay=0 Test