This study addresses a critical gap in the educational technology literature by empirically comparing the effects of linear and interactive instructional videos on students' technology acceptance and learning retention in an informal learning environment. Employing a mixed-methods design, a within-subjects experiment was conducted with 55 university students who engaged with both video formats. Quantitative data, collected via a Technology Acceptance Model (TAM) questionnaire and a multiple-choice retention test, were analyzed using a paired t-test. The results show that students' technology acceptance (t(54) = -10.31, p < .001) and learning retention (mean score of 5.60 vs. 4.56) were significantly higher for the interactive video format. The qualitative phase, which involved twelve semi-structured interviews, identified seven key mechanisms that explain these positive outcomes, including enhanced perceived usefulness, improved ease of use, increased engagement, and support for personalized learning. These findings contribute to the field by providing a clear rationale for the pedagogical superiority of interactive videos and offering a practical framework for educators and designers to create more effective and engaging digital learning materials.