Show a WebCamTexture with alpha

Hi.
Is there any way of displaying the output of a WebCamTexture half transparent ?
This is what I’m doing:

webcamTexture = new WebCamTexture();
deviceCamera = new GameObject("Camera output");
deviceCamera.transform.position = Vector3.zero;
deviceCamera.AddComponent<GUITexture>();
deviceCamera.guiTexture.enabled = true;
deviceCamera.guiTexture.pixelInset = new Rect(0f,0f,Screen.width,Screen.height);
deviceCamera.guiTexture.texture = webcamTexture;
webcamTexture.Play();

Funny thing is, when I change the alpha property in the inspector it actually works but only in the Scene view, not in the Game view (see picture attached).
I assume it’s setting a blue background automagically somewhere.

I needed to change the alpha value of the GUITexture colours.