I've been using it a lot and it works very well, but it's a cli app. You can get a Chrome/Firefox app that gives you a button on your browser bar and sends the URL to whatever page you want to catt, that's a good way to cast anything youtube-dl supports to a Chromecast.
It amazes me that Google hasn't made a similar pieces of software for viewing x video format... The fact you have to use weird 3rd party stuff just to watch a movie you downloaded is strange to me.
It would instantly make Chromecast 10x more useful. But Google is focused with keeping it for streaming sites and browser pages only for some reason.
If they want to keep people using the stuff that has ads on it, then you have to make sure it works for every other scenario too. Otherwise people will replace it entirely.
I'll give this a shot...