- The view starts ready to hand a page off, so "Watch on YouTube" clicked
  before the embed has finished loading still opens in the browser. After a
  hand-off only a finished embed load re-arms it, which still stops a
  redirecting embed address from opening tabs forever.
- Start-time numbers are capped at six digits; t=9223372036854775808
  overflowed int.parse and crashed the video slide.