BENGALURU, Feb 17 (Reuters) - Indian telecom operator Bharti Airtel Ltd said on Wednesday it will buy a 20% stake in its direct-to-home television arm Bharti Telemedia from U.S. private equity firm Warburg Pincus for 31.26 billion rupees ($429.31 million). ($1 = 72.8140 Indian rupees) (Reporting by Philip George in Bengaluru; Editing by Shounak Dasgupta)