I know, friday 13, bla, bla, but this works great! VidCast: Chromecast for the rest of the web.
It works with: Vimeo, TED, and tons of other sites.
The first I tried is was a great half hour Devopsdays Amsterdam 2015 session “Leslie Hawthorn – Fear of Failing Fast: How to Avoid Sabotaging Your Success”
The easiest way is to drag the VidCast bookmarklet button to your bookmarks bar once, then for videos you want to watch: