YouTube has grown into an unprecedented music industry where informal learning practices converge among young musicians now considered authentic internet (micro)celebrities. Due to the rise of music video trends on the platform and the educative demands to explore youth interaction on the internet, this study analyses the self-perception of youtubers in terms of multimedia, hypermedia, intertextual and transmedia competencies. For this purpose, we developed a questionnaire on musical competencies (TransMuQ), in which 603 young youtubers from Spanish and English-speaking countries participated. We found that YouTube's performers consider themselves proficient in the aesthetics, participation and interaction, multimodal languages, technology, content creation and risk and individual management dimensions. After an extensive theory on the experimental analysis of these competencies in citizenship, we propose a new approach towards interactive codes of young YouTube musicians. The research provides a clarifying positivism about what youtubers themselves believe they are learning in the era of ephemeral digital content.