Try disabling youtube.
Add youtube.js.
Trying to include youtube.js...
Still trying...
Still trying...

This time, trying to follow suggestion from Rails:

Sprockets::Rails::Helper::AssetFilteredError at /refinery/videos/4
Asset filtered out and will not be served: add
`Rails.application.config.assets.precompile += %w( youtube.js )` to
`config/initializers/assets.rb` and restart your server
Restore HTML and Flash playback.