Xianghui team

Watch Once turns one video of a hands-on task into a coach that watches anyone else do it. Hands-on skills like assembly, repair and kitchen prep are still taught by someone standing over your shoulder. Watch Once replaces that with a single reference video: your best technician on camera, or an existing tutorial, even a silent edited one. It learns the ordered steps from that video. Then anyone can upload their attempt, or turn on their camera and work while it watches. It tells them which steps they skipped, did out of order, or got wrong, with the exact moment, an outlined frame as evidence, and the expert’s clip of how it’s done. Live mode speaks up within around 3-6 when a step is missed, and pressing Stop runs a full review of the whole session. Tested on real footage (a Nutella sandwich and a RAM install in a mini PC): correct attempts score 8/8 and 5/5 with no false alarms, and a flawed attempt had all of its mistakes caught. Everything was built during the hackathon.