In your video I see a bad workflow: before meshing any surface make sure you have prescribed attributes to the geometry using command "Mesh > Mesh Control > Attributes in Surface", this should be you first step. Next you can issue command "Mesh > Geometry > Surface" and select ALL surfaces of your NonManifold Sheet Body using METHOD=ON SOLID, only one meshing command, then FEMAP will mesh every surface with its corresponding material & thickness property, not need to go one by one.
But the benefits of the above workflow will be more: later when you copy the sheet body using "Geometry > Copy > Solid" command you need to make sure to select ON the "Mesh Sizes, Loads & Constraints" option, this way you can mesh directly the new copied surfaces geometry because you have both the surfaces attributes & mesh sizings in curves, not need to copy the mesh and associate to the geometry, OK?.
If you don't follow the above meshing approach then FEMAP will mesh the copied surface geometry using PLOT ONLY elements, then the error ..
Blas Molero Hidalgo, Ingeniero Industrial, Director IBERISA • 48004 BILBAO (SPAIN) WEB: http://www.iberisa.com Blog Femap-NX Nastran: http://iberisa.wordpress.com/