Who's data does a chromecast use?

[kegnkiwi]

I'm heading off on holiday in a couple of weeks and I'm thinking of taking a chromecast with me to stream movies off my phone to a tv therefore not tethering and breaking the phone providers t&c's. I updated an old chromcast last night but it asked me for access to my virgin router but if did not ask for a password. So i am trying to work out if it was using the house internet or my phone was using the data then sending it to the chromecast. I can test myself with other routers not connected to the net but I thought I would ask the question.

 

[sneaker]

They do connect to virgin or whoever Your net is supplied by, so it can give You offers like free films etc. If mirror casting from your phone however the stream will come from the phone.