YouTube's policy on reused content specifically affects channels built around reactions, compilations, or clips from other sources.
The Core Requirement
Videos using others' content generally need substantial original commentary, analysis, or educational value added on top of the reused material.
Common Pitfall
Simply playing a clip with minimal added commentary is a frequent reason such videos lose monetization eligibility.
Self-Check Before Uploading
A useful gut check: would your video still have meaningful value if the reused clip were removed and only your commentary remained?