While live event experiences have become increasingly mediatized, the prevalence of ephemeral content and diverse forms of (semi)private communication in social media platforms have complicated the study of these mediatized experiences as an outsider. This article proposes an ethnographic approach to studying mediatized event experiences from the inside, carrying out participatory fieldwork in online and offline festival environments. I argue that this approach both stimulates ethical research behavior and provides unique insights into mediatized practices. To develop this argument, I apply the proposed methodology to examine how festival-goers perceive differences between public and private, permanent and ephemeral when sharing their live event experiences through social media platforms. Drawing on a substantial dataset containing online and offline participant observations, media diaries, and (short in situ and longer in-depth) interviews with 379 event-goers, this article demonstrates the value of an ethnographic approach for creating thick descriptions of mediatized behavior in digital platforms.