module ActionView::Helpers::AssetUrlHelper

video_url "hd.avi", host: "http://stage.example.com" # => http://stage.example.com/videos/hd.avi

options is set, it overwrites global +config.action_controller.asset_host+ setting.
Since +video_url+ is based on +asset_url+ method you can set +:host+ options. If +:host+
This will use +video_path+ internally, so most of their behaviors will be the same.
Computes the full URL to a video asset in the public videos directory.

def video_url(source, options = {})
  url_to_asset(source, { type: :video }.merge!(options))
end