Fix VideoCutscene checking by loading the videos OpenFL library

Author: TechnikTil

source/funkin/play/cutscene/VideoCutscene.hx

@@ -73,13 +73,10 @@ class VideoCutscene
     if (!openfl.Assets.exists(filePath))
     {
       // Display a popup.
-      // funkin.util.WindowUtil.showError('Error playing video', 'Video file does not exist: ${filePath}');
-      // return;
-
-      // TODO: After moving videos to their own library,
-      // this function ALWAYS FAILS on web, but the video still plays.
-      // I think that's due to a weird quirk with how OpenFL libraries work.
+      funkin.util.WindowUtil.showError('Error playing video', 'Video file does not exist: ${filePath}');
       trace('Video file does not exist: ${filePath}');
+
+      return;
     }
 
     var rawFilePath = Paths.stripLibrary(filePath);

source/funkin/ui/transition/LoadingState.hx

@@ -95,6 +95,7 @@ class LoadingState extends MusicBeatSubState
       }
 
       checkLibrary('shared');
+      checkLibrary('videos');
       checkLibrary(stageDirectory);
       checkLibrary('tutorial');