I've uploaded a small video (it's still private).
No audio, for now. The resolution at full screen is not great (it is my first YouTube upload. Locally, the .webm video looks much better)
The video assumes you are familiar with mmj2
It mainly shows diagnostics, syntax suggestions and step suggestions (and step derivation, but this is like in mmj2)
Here are a list of shortcuts used in the video (VSCode in Ubuntu):
ctrl+n (new file)
ctrl+s (save file)
ctrl+z (undo)
ctrl+u (unify)
ctrl+n (unify and renumber)
ctrl+space (trigger step suggestions)
downarrow and uparrow (navigate through completion items)
tab (select current completion item and unify)
Here's the link