Update C# example on Playing videos

tutorials/animation/playing_videos.rst

@@ -268,7 +268,7 @@ To implement the chroma key effect, follow these steps:
 
 2. In the "ChromaKeyShader.gdshader" file, write the custom shader code as shown below:
 
-.. code-block:: gd
+.. code-block:: glsl
 
    shader_type canvas_item;
 
@@ -343,11 +343,6 @@ To allow users to manipulate the chroma key effect in real-time, we created slid
         public override void _Ready()
         {
             _videoStreamPlayer = GetNode<VideoStreamPlayer>("VideoStreamPlayer");
-            _videoStreamPlayer.Finished += OnVideoStreamPlayerFinished;
-
-            GetNode<ColorPickerButton>("ColorPickerButton").ColorChanged += OnColorPickerButtonColorChanged;
-            GetNode<HSlider>("HSlider").ValueChanged += OnHSliderValueChanged;
-            GetNode<HSlider>("HSlider2").ValueChanged += OnHSlider2ValueChanged;
         }
 
         private void OnColorPickerButtonColorChanged(Color color)