A method is provided for a personalized content delivery system. The method includes detecting a viewing activity of at least one user of a content-presentation device capable of presenting multiple programs in one or more channels, and determining a plurality of user identities of the at least one user. The method also includes discovering available video contents for the at least one user based on the plurality of user identities, and determining personalized video contents for the at least one user by merging the plurality of user identities. Further, the method includes recommending the determined personalized video contents to the at least one user, and delivering the recommended personalized video contents to the at least one user such that the personalized video contents are presented on the content-presentation device.