I would recommend opening the Sublime console with Ctrl+` and entering the following commands:
sublime.log_commands(True)
sublime.log_input(True)
Once you’ve done that, try to replicate your problem from the screencast. Normally, you would see something like the following printed in the console every time you press the Left key:
key evt: left
command: move {"by": "characters", "forward": false}
From the looks of your problem it almost seems like some sort of weird key bind problem where the movement command is bound to ["left", "left"]
instead of just ["left"]
or something along those lines. That would present as two key evt: left
lines before the command triggers, for example.
The output in the console will help narrow down what might be happening.