Nice, thanks so much for the video. It's so interesting to see someone else playing the game and trying to figure things out, it's difficult for me to visualize how a puzzle might be solved since I already know the solutions so videos are invaluable for me.
You said you only understood the blue blocks later in the game and your video helped me understand why, you seem to have learned it in level 5 (second in the video) once you were forced to go around the pinned box to place the blue block in the bottom right corner, I think I will be making a simpler version of this level earlier on since it seems to be effective, other people who played the game also seemed to be more comfortable once they played that level.
Again, thanks a lot!