I know the video, again it doesn't matter. I speed type on my phone exactly the same way I used to. I understand how autocorrect works and that it retroactively fixes multiple words later on. I typed this whole comment on my iPhone and I encountered no such issue.

What the video shows could be a problem only if you disable autocorrect or if you want to type a single letter. I made a bunch of errors typing this one and in the end the phone autocorrected it all.