Peer tutor learning has been effectively adopted in various learning contexts. It draws attention from the CHI community as it has the potential to be advanced through computer-mediated online video technologies. In this paper, we focus on understanding how Q&A (questions and answers) between tutors and their students is used to promote learning using online videos. Building upon our prior work, we designed and implemented a new Q&A interaction. Through conducting a field study and a follow-up survey of 47 graduate students, our research reveals gaps between a peer tutor’s strategy (i.e., question position and knowledge type) and a learner’s preference and answering effort. For example, compared to tutors, learners preferred that questions be inserted in the middle of the videos and that the answers to tacit knowledge-related questions be more numerous and longer than those for explicit knowledge-related questions. The design implications from our findings need to be incorporated into practice and into future research of online videos for peer tutor learning.