We present the initial design and evaluation of Kalgan, an interactive video player tailored to support casual language learning. Unlike traditional, more structured learning, casual language learning takes place alongside existing leisure activities such as watching videos. To better support learning during casual video viewing, we introduce several new features, including subtitle-aware rewind, interactive subtitle translation, and word lookup history that help people quickly access language content and recover missed information without disrupting their viewing experience. We evaluated this initial version of Kalgan using a mix of remote studies and in-person observation. The results of the evaluation highlight our participants’ enthusiasm for subtitle-centric learning aids. They also suggest a variety of future research opportunities for casual language learning tools.