I've been using vim as my primary editor for a few years now and I love how there's always something new that just blows my mind, like the :earlier and :later in that pinned tweet.
Didn't know that you could just use 'A' to append to the end of a line instead of doing '$a'. Neat!
Similarly, 'I' will move the cursor to the start of the line and then enter insert mode.
Apropos my comment above, that command has lived in my vi/vim blind spot.
Strangely 'A' and 'i' were the first two things I learned, and probably the only for a long time. It is interesting what seems obvious to one vi/vim user becomes a new trick to another, different needs etc I suppose.
How do they show the keystrokes on the screen? Is it an app or they edit it in?