Well, I use CATT from a rpi to cast a live view "page" from a Bosch
security camera to a Nest Nub and that is now also stopped after 30s.
Some time ago it played until I stopped it with CATT. So I do think the
"fix" needs to be implemented in CATT .....
When I use the chrome browser on a PC to cast a website to a
chromecast/nest hub, there is no 30 sec timeout! It is only there when
using CATT to cast a website.