Against the background of deepening population aging and active aging strategy in China, this study focuses on the digital divide and insufficient age-friendly English teaching resources for elderly learners on Douyin. Based on age-friendly design, adult learning, educational technology, and cognitive theory of multimedia learning, this study constructs a three-dimensional framework including age-friendly experience, learning support, and motivational interaction. Using literature research, questionnaire survey, textual analysis, and empirical research, this study explores design defects, core elements, and optimization paths of age-friendly English teaching videos. Results show that current videos are incompatible with elderly outbound travel scenarios, with high sensory and operational barriers and a lack of emotional motivation. Four core design elements are extracted, and empirical videos verify that the proposed strategies significantly improve completion rate, interaction rate, and user acceptance. This study enriches the application of age-friendly theory in short-video language teaching and provides practical references for platforms and creators to support elderly English learning and a lifelong learning society.