It seems to depend on the device. I was able to Cast from Chrome on a Windows 10 Laptop to a Chromecast without any issues while connected through the VPN, but I couldn't get it to work from an Android phone. It appears that Android won't send that traffic over a the VPN. If I run packet...
I know this post is old, but figured I'd leave this here since I was unable to find this already compiled anywhere else. I used the source from the website in OP (http://irq5.io/2011/01/02/mdns-repeater-mdns-across-subnets/) which links to https://bitbucket.org/geekman/mdns-repeater/
It was...