I just checked that video (which is correct btw) - make sure both checkboxes on the Detach dialog are unticked.
As for the scale, set both the system units and the display units (to the same values i.e. Metric and Meters) before you start modeling.
Max 2016 (SP1/EXT1)
Win7Pro x64 (SP1). i5-3570K @ 4.4GHz, 8Gb Ram, DX11.
nVidia GTX760 (2GB) (Driver 430.86).