This paper describes an adaptive IP-unicast-based multicast protocol that dynamically constructs a multicast tree based only on request packets sent by clients. Since the protocol is simple but flexible and does not require any IP multicast addresses or special multicast mechanisms, unlike the IP multicast protocol, it is scalable and suitable for personal stream broadcasting and related services. An application that dynamically attaches advertisements to multicasted streams is also presented. The application attaches advertisements to the streams at active nodes instead of the server so it can deliver advertisements tailored to the individual recipient, according to his/her interests and/or location. An algorithm that minimizes the attachment cost over the corresponding multicast tree is developed. The multicast and advertisement attachment mechanisms are implemented using our own active network environment, and their validity is confirmed.