Comcast Corp. added video customers in its fourth quarter, its first gain in that business in six-and-a-half years.

Comcast has been investing in new products and customer service to morph from a cable company to a technology company, Chairman and CEO Brian Roberts told investors Tuesday at the Citi Internet Media & Telecommunications Conference.

Roberts said that the moves are paying off as Comcast "modestly" grew its base of video customers in its fourth quarter. This follows a decline in video subscribers for 26 straight quarters.

"It will take some time before the entire year will grow but it is a real beginning of an exciting reversal of trends," Roberts said.

Comcast, the nation's largest TV and Internet provider, ended its third quarter with 21.6 million video customers.