Ok, I understand it now.
You set up the LOD. You add the Trees, Low, Med, High etc.... THEN you set up your normal forest scatter with the LOD selected as the distribution object. Set up the Normal Forest Scatter way you want it to look as per normal. You then go back to the LOD and amend for just LOD purposes.
I felt the tutorial skipped over this a little or, I am a little slow this morning.