Gameplay spectatorship has developed signifcantly over the last decade, necessitating the need to design more engaging spectator experiences. In order to do this efectively, however, we must frst better understand spectator behavior and motivations. In this paper, we build on the results of a previous work examining interaction preferences of remote livestream spectators depending on their user type, and report a new qualitative study exploring the underlying motivations that shape the experience of those engaged in interactive spectating. Our results highlight fve main themes (entertainment, team support, learning, caster, social) that motivate spectators to engage with interactive esports experiences. This work will motivate ongoing research in this domain by promoting conversations about livestream spectator engagement and motivations, and facilitating engaging spectator experiences.