GoogleWebComponents/google-youtube — pull request #10 by jeffposnick (2014-09-18 17:29:12+00:00)
Title: Support for custom thumbnails

@ebidel @addyosmani @robdodson

- Adds a `thumbnail` attribute that can be set to the URL of a custom thumbnail image to use.
- Added another couple of tests to cover custom thumbnail behavior.
- Hopefully cleans up some element sizing inconsistency, in that the YouTube `