The inclusion of videos in teaching has become widespread in the last decades. The paper faces the question of whether this practice should be considered beneficial to learning in any case, due to the attractiveness of audio-visual resources. Studies in cognitive psychology offer a complex answer: on the one hand, the double channel -sight and hearing -is a motivating device; on the other hand, the exposure to the two language codes, images and commentary, may cause cognitive overload in working memory, hindering long-term meaningful retrieval. Examples from the author's experiences of teaching English as a second language to undergraduates show how a teacher may endeavour to emphasise the attractiveness of the medium and, at the same time, reduce or even avoid memory shortcomings. To ensure beneficial effects, criteria to follow when choosing a video are underlined, as the overall consistency between the visual and the verbal codes. To weaken the critical effects, attention is drawn on the following aspects: the role of videos to activate or create learners' cognitive and language 'schema' before approaching a new topic; the selection of comprehension strategies according to the educational objective, rather than a thorough understanding of the video clip. The paper concludes focusing on the need for learners to be aware of the rationale behind both the choice of video clips and of comprehension strategies, in order to encourage autonomous learning in an academic context, as well as in everyday life.