Learning to play music is an embodied process, but traditional tools like scores and recordings overlook the role of gesture. While video tutorials offer visual cues, they remain detached from the instrument. We present ReTouche, an interactive system that projects synchronized notes and hand gestures directly onto the actuated keys of a player piano. The system includes a pipeline for adapting publicly available overhead-view YouTube videos and supports interactions for video-based learning, such as sectional practice, layered guidance, and self-recording. We evaluate ReTouche through a comparative structured observation study with YouTube-based self-learning (n=18), a two-week autoethnography study (n=3), and a focus group with professional piano teachers (n=4). Our findings show that embodied representations can ground self-guided piano learning by anchoring gesture, sound, and action within the instrument. Learners appropriated these representations to develop strategies and sustain motivation, while teachers saw potential for integrating ReTouche as a complement to conventional pedagogy.