Phone [Q] Use mobile data while connected to wifi

I would like to be able to stream netflix over 4G while connected to a wifi point that has no internet to stream to chromecast.This would allow me to watch netflix while traveling on the hotel TV using the Asus WL-330NUL ( I can't link it yet).

Alternatively if anyone knows how to adhoc connect with chromecast that would be cool (But this is the wrong forum for that)

I have googled both of these issues and searched the wifi issue on XDA so hopefully this isn't a repeat.
I am not rooted since I have JUMP and that would void it but I have rooted all my other phones.