I think Ableton is set up correctly (except for monitoring “In” ), i.e. track #1 is set to receive MIDI Channel #1, track #2 to MIDI Channel #2 and so on.
Are you sure that when you switch to channel 2 on Novation SL it actually sends the corresponding notes on MIDI Channel #2? In your video there was never any activity on either the sequencer of Novation SL or in Live’s track #2.
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