The rise of mobile technology has transformed the once passive activity of watching a live sports broadcast into an active experience. Nowadays, it is common practice for sports fans to communicate, interact and share information with others through social mobile applications not only after, but also during the broadcast of a live sport event. However, sometimes the discussion between fans is not contextualised and the social applications used by them lack tools to register moments that can promote social discussions. Furthermore, not all sports fans can watch an event TV broadcast, making it impossible to express a concrete opinion about it. To address this issue, we developed ReactIt, a system developed for smartphones and smartwatches, that allows users to share automatically generated videos containing specific moments of a football match along with their emotional reaction, to engage fans and promote social interaction between them. Results from user tests were very positive regarding the interaction with both devices, and users manifested great interest in using ReactIt in a real life environment.