You must play all three instruments when someone from the crowd is recording. The audience member will hold up a phone/camera in the bottom right corner and a countdown from three will begin. When the recording starts you must play all three instruments in the time limit. Each instrument only has to be played for a second and then you can switch. To switch, you put your arms at your side so that you're standing straight and the instrument that you were playing will disappear. You can then start playing the next instrument. After the recording is done, you can immediately share the video by pausing the game. From there click Share and upload it.