Open online education has become increasingly popular. In Massive Open Online Courses (MOOCs) videos are generally the most used method of teaching. While most MOOCs are offered in English, the global availability of these courses has attracted many non-native English speakers. To ensure not only the availability, but also the accessibility of open online education, courses should be designed to minimize detrimental effects of a language barrier, for example by providing subtitles. However, with many conflicting research findings it is unclear whether subtitles are beneficial or detrimental for learning from a video, and whether this depends on characteristics of the learner and the video. We hypothesized that the effect of 2nd language subtitles on learning outcomes depends on the language proficiency of the student, as well as the visual-textual information complexity of the video. This three-way interaction was tested in an pre-registered experimental study. Using Bayesian analyses, no main effect of subtitles was found, nor any interaction. However, the student's language proficiency and the complexity of the video do have a substantial impact on learning outcomes.