Thanks for sharing this Dan!
I wanted to highlight this for @tswietochowska because she asked a question a month or so ago in this thread App selectable date range in analytics - and I think your example here is another great way to accomplish the goal in this question.
The other thing I love that you highlight (around 8:30) is the difference between using “equals” and “contains” for filtering and how it can make your analysis much more useful just by choosing contains, which does not search for exact match (whereas equals does search for exact match).