In theory, what you'd need to do is:
instead of including easyrtc.js in your header,
include Temasys's adapter.js, and easyrtc_int.js and easyrtc_lang_en.js in the bottom of the document body
The multiple file inclusion is because easyrtc.js is actually the concatenation of our own adapter.js, easyrtc_int.js, and easyrtc_lang_en.js. Our own adapter.js is the standard one with a bit better handling of version numbers (something put in by an easyrtc user who was using unusual software). The file inclusion has to go into the body because the adapter injects their plugin into the body of the document and that fails if the body hasn't been loaded yet.
Then, as long as you aren't referencing the rebuilt video objects too soon after page load, you should be fine.
In practice, I spent a little bit of time a few weeks ago trying to get this to work with demo_audio_video.html and was unsuccessful. There was a fairly mundane call in their code that was replacing the video tags, a call that was failing for no reason I could see. I hope you'll post your own experiences. Bistri.com uses the Temasys adapter and it seemed to work well.