If you are embedding a DaCast video player on a Google Site and want to use the iframe, make sure the http is set to https. For example,
<iframe src="https://iframe.dacast.com/beta/b/###/c/###" width="640" height="480" frameborder="0" scrolling="no" allowfullscreen webkitallowfullscreen mozallowfullscreen oallowfullscreen msallowfullscreen></iframe>
Here we have added an "https" before the :// which will prevent the Google Site from generating a security warning.
Just for reference, the security warning you will get if you leave the http in will look something like this:
"The page at 'https://www.***.***/'; was loaded over HTTPS, but displayed insecure content from 'http://services.viewer.dacast.com/crossdomain.xml': this content should also be loaded over HTTPS. "