Files used: http://areadownloads.autodesk.com/wdm/maya/HTM_SHD_Trilobot.zip
For Maya 2018, use files: http://areadownloads.autodesk.com/wdm/maya/HTM_SHD_Trilobot2018.zip
Arnold 5 is provided with Maya 2018. If you are following this tutorial with Maya 2018, use the aiShadowMatte shader in lieu of the aiShadowCatcher shader (8:17 and 9:47).
(9:47) When using the aiShadowMatte shader, you do not need to perform the extra step of enabling Enable Transparency in the shader Attribute Editor.
This video introduces you to the basics of the new render setup system. It describes how to divide a scene into render layers, populate layers with collections, and create overrides for each collection.