I see that they used:
<div class="play__button__container" on-tap="{{openMastheadVideo }}" data-link-track="home-watch-keynote-masthead"><h5>Watch the keynote</h5> </div>
But nothing in Polymer Catalog that helps me understand this.
I tried using `google-youtube` but I can't use the material designed play button...instead the default youtube playbutton is used. Also, I want to do the video full screen horizontally and about 400px vertically. But when I use
<google-youtube
video-id="YMWd8E"
height="400px"
width="100%"
rel="0"
start="5"
playsinline="0"
controls="0"
showinfo="0"
autoplay="0">
</google-youtube>
It zooms into the video still rather than proportionally displaying it like the google i/o site header with the speaker holding the microphone.