* Add new video properties frontmatter
* Handle video links in the middleware
* Video links don't have intros, authors, or full titles
* Make videos available from context
* Add default video heading
* Add basic tests for videos
* tmp videos test
* Remove stray test debugging
* more tmp videos testing
* Add videos test fixture
* Revert "more tmp videos testing"
This reverts commit 382946a5603ff217014797f77f37216bb8bb6c9c.
* Revert "tmp videos test"
This reverts commit 8767d0eaf08bd4ca04e2dacd12d476a2506c0367.