Keys: 1234 / QWER / ASDF / ZXCV, Space = play/stop. One video plays at a time, so the newest hit cuts the previous.
Next sequence queues a switch at the end of the current loop, so the change lands in time.
Chops the selected pad's start–end window and assigns each region to consecutive pads from the selected pad. Play the video, tap Mark now on each hit, then chop at marks.