Less than a week after promising its users an upgrade that’ll let them search and watch YouTube videos later this year, TiVo has added the capability for its subscribers to watch some video content from the Web. TiVo first promised the new service, which is immediately available, in January. TiVo already offers TV shows and movies that are available on Amazon Unbox and music via RealNetworks’ Rhapsody service. Users can also access and view videos stored on their PC. They can copy TV shows and movies recorded on a TiVo DVR to their portable devices. The Internet-related services require that the TiVo be connected to an Internet-connected PC that’s running TiVo Desktop Plus PC version 2.6 software. TiVo seems determined…