The relationship between political YouTube news use and affective polarization in election vs. non-election contexts: mediation by hostile expression and moderation by political rumor acceptance

User-generated political YouTube channels often disseminate conspiracy narratives and partisan information, potentially reinforcing echo-chambers and intensifying hostility toward political outgroups. Against this backdrop, this study examines the interplay among political YouTube channel-based news use, hostile expression, affective polarization, and acceptance of political rumors across different political contexts. Using nationally representative online survey data from South Korea collected in a non-election period (2021) and an election period (2024), we found that the interaction between political YouTube channel-based news use and acceptance of political rumors was not significantly associated with hostile expression in the non-election context, but it was positively associated with hostile expression in the election context. We also found that individuals who frequently used political YouTube channels and were more accepting of political rumors were more likely to engage in hostile expression, which in turn was associated with higher levels of affective polarization during the election period.