Okay, first off, I'm a totally new Blender 2.8 user. I'm pleased that so much of what I've encountered is very intuitive. But the one thing that I'm having trouble wrapping my head around is changing the material. Starting with just the default cube: I found the Materials palette, changed the Base Color, and it's still just a grey-white cube. This seems to conflict with every tutorial I've seen -- the cube should change to match the color. On a lark, I turned off Use Nodes, and then suddenly my color appeared, but many of the other options in the Material palette go away. Turned Use Nodes back on, and I'm back to a grey-white cube. Is this a bug, or am I missing some step?
You probably have the solid display button on and haven't pressed the render button. In the video you mention there are several buttons at the top right of the 3d viewport that are associated with overlays and displays like wireframe, solid, lookdev, render, and shading -- note that the render button, just to the left of the shading drop down menu, is turned on. BY the way, on my 2.8 beta version all those buttons are at the bottom right of the 3d viewport.