The real magic of ido is the completion engine. It's not made super explicit in that video, but it's actually possible to complete on arbitrary subsequences of strings you want.

With my configuration (using the popular "flx-ido" matching engine), if you wanted to match "README.md", you could achieve this by just typing ED. Even though E and D aren't consecutive, E appears before D. (But "GOOD_EDITING_SOFTWARE" would be matched before "README.md", because it prioritizes consecutive matches and characters at the beginnings of logical groups of characters.)