Don’t worry if you don’t understand something completely; 3D modelling is very hard and there is really a lot to learn and I think there will always be some things you don’t get in a beginner’s course that tries to cover all the basics.
Just re-watch this course in a year or so and you will be able to understand most, if not everything. Also, you are likely to forget some of the things that are not clear to you now and that way you will be reminded of those.
To be honest, I have used Blender for about 8 years without understanding Autosmooth (if something looked strange when shaded smooth I just turned on Autosmooth and maybe changed the Angle if necessary) or Custom Normals and only learned what happens when this course came out….
You already have an advantage over me there;)
