Work? Probably.

Legal? Grey area at best. My opinion is one of those services that tap into someone's streaming and distribute it, with no rights acquired. I'd be wary of any scripts of ads injected.

from what i could see its a digital antenna ? 

Search further and you will find the service. Two different things with same name.

This addon for Firefox?

https://addons.mozilla.org/en-US/firefox/addon/tv-fox-watch-tv-online/