exclusively use WEB client + force inv_sig_helper usage

src/invidious/config.cr

@@ -220,6 +220,13 @@ class Config
         end
     {% end %}
 
+    # inv_sig_helper is now mandatory due to exclusive usage of WEB
+    if !config.signature_server
+      puts "Config: inv_sig_helper is mandatory. Please configure it by following \
+            the official documentation: https://docs.invidious.io/installation/"
+      exit(1)
+    end
+
     # HMAC_key is mandatory
     # See: https://github.com/iv-org/invidious/issues/3854
     if config.hmac_key.empty?

src/invidious/videos/parser.cr

@@ -53,10 +53,8 @@ end
 def extract_video_info(video_id : String)
   # Init client config for the API
   client_config = YoutubeAPI::ClientConfig.new
-  # Use the WEB_CREATOR when po_token is configured because it fully only works on this client
-  if CONFIG.po_token
-    client_config.client_type = YoutubeAPI::ClientType::WebCreator
-  end
+  # Exclusively use WEB now
+  client_config.client_type = YoutubeAPI::ClientType::Web
 
   # Fetch data from the player endpoint
   player_response = YoutubeAPI.player(video_id: video_id, params: "2AMB", client_config: client_config)
@@ -106,32 +104,13 @@ def extract_video_info(video_id : String)
 
   new_player_response = nil
 
-  # Second try in case WEB_CREATOR doesn't work with po_token.
-  # Only trigger if reason found and po_token configured.
+  # Second try in case WEB doesn't work.
+  # Only trigger if reason found .
   if reason && CONFIG.po_token
     client_config.client_type = YoutubeAPI::ClientType::WebEmbeddedPlayer
     new_player_response = try_fetch_streaming_data(video_id, client_config)
   end
 
-  # Don't use Android client if po_token is passed because po_token doesn't
-  # work for Android client.
-  if reason.nil? && CONFIG.po_token.nil?
-    # Fetch the video streams using an Android client in order to get the
-    # decrypted URLs and maybe fix throttling issues (#2194). See the
-    # following issue for an explanation about decrypted URLs:
-    # https://github.com/TeamNewPipe/NewPipeExtractor/issues/562
-    client_config.client_type = YoutubeAPI::ClientType::Android
-    new_player_response = try_fetch_streaming_data(video_id, client_config)
-  end
-
-  # Last hope
-  # Only trigger if reason found or didn't work wth Android client.
-  # TvHtml5ScreenEmbed now requires sig helper for it to work but doesn't work with po_token.
-  if reason && CONFIG.po_token.nil?
-    client_config.client_type = YoutubeAPI::ClientType::TvHtml5ScreenEmbed
-    new_player_response = try_fetch_streaming_data(video_id, client_config)
-  end
-
   # Replace player response and reset reason
   if !new_player_response.nil?
     # Preserve captions & storyboard data before replacement