This app is the free version West Coast Swing Dance On Time Pro

The app consists of a video recorder with metronome and strobe light, and video player with frame and beat advance controls so you can easily see if the timing of your steps matches the drum beats.

During video recording of your dance step, the app plays a dance beat metronome at 90 BPM with a flash on the whole beats.

The app’s video player has controls for frame and beat or step advance for easy review of dance videos.

If dancing off time, the Pro version adds dance beat adjustment from 30 - 160 BPM. It is easier to dance on time at a slower beat, and gradually work up to full dance speed.