This issue has been resolved in Unity 4.2.1 and only effects Unity 4.2.0, upgrade to the latest Unity to resolve the rendering bug detailed below.
Unity 4.2.0 has a rendering issue when using the MovieClipBehaviour, this causes sub-meshes to blend in the wrong order.
1. Download uniSWF1.0.5_rc6 from the download area.
2. Update LibUniSWF.dll and LibUniSWFEditor.dll from the unity package.
3. creating a new game object, add the UniSWFDeveloperOverrides component.
4. Enable _devTempUnity42DrawMeshOverrideHack flag
5. Change script execution order of the UniSWFDeveloperOverrides to ensure executes before the MovieClipBehaviour.
To enable through code, set the following static variable before any MovieClipBehaviours.Awake() is called:
MovieClipBehaviour._devTempUnity42DrawMeshOverrideHack = true;