examples are in the tests

app/services/video/provider/dailymotion.rb

 class Video::Provider::Dailymotion < Video::Provider::Default
   DOMAINS = ['dailymotion.com', 'dai.ly']
 
-  # "https://www.dailymotion.com/video/x35l6b8"
-  # "https://dai.ly/x35l6b8"
   def identifier
     video_url.include?('dai.ly')  ? video_url.split('dai.ly/').last
                                   : video_url.split('video/').last

app/services/video/provider/vimeo.rb

 class Video::Provider::Vimeo < Video::Provider::Default
   DOMAINS = ['vimeo.com']
 
-  # "https://vimeo.com/248482251"
   def identifier
     video_url.chomp('/').split('/').last
   end

app/services/video/provider/youtube.rb

 class Video::Provider::Youtube < Video::Provider::Default
   DOMAINS = ['youtube.com', 'youtu.be']
 
-  # "https://www.youtube.com/watch?v=sN8Cq5HEBug"
-  # "https://youtu.be/sN8Cq5HEBug"
   def identifier
     video_url.include?('youtu.be')  ? video_url.split('youtu.be/').last
                                     : video_url.split('v=').last