Common terminology for review comments
Replace tag/label with type, and an example.
Updates to video events for mobile
Merge pull request #5529 from edx/ahodges/doc/DOC916mobile

Updates to video events for mobile
Merge pull request #5236 from edx/pull-requests/review

Common terminology for review comments
Remove references to /tmp in tests

Including:

* Change path for mongo_metadata_inheritance to use unique temp dir
* Update SASS_CACHE_PATH with thread-safe temp dir
* Remove hard coded directory reference for grades download tests
* Remove hard coded directory reference for direct mongo test