I don't quite understand why you would want to purchase an adapter to control your existing tv box via the xboxo? The tv unit and the xboxo would be both consuming power just so you can flail your arms, or give a speech command rather than pressing 101 etc? Nah.
I dont think its an adaptor as such. I think they mean a cable provider box. The Xbox One wont have a Sky or Virgin or anyone elses cable/sat tuners.