This Ableton-produced clip walks through the core loop controls available for MIDI clips in Live's Detail view, covering the Loop switch, Loop Length, Loop Position, and loop duplication in a single focused demonstration.
Toggling the Loop switch determines whether a clip repeats continuously or plays through just once. The Loop Length and Loop Position controls let you resize and reposition the loop brace numerically, and you can also grab the brace directly in the Clip view and adjust it while the clip is playing.
The Start marker sets where playback begins within the clip and is also movable in the Clip view. Hitting Duplicate Loop, or selecting the loop brace and pressing Cmd/Ctrl+D, copies the loop content and doubles its total duration.