[Support request] stuck point

Is there a video that explains how our professor gets to the final stuck point, especially for the harder puzzles? One that does a verbal, point by point explanation? Often it seems that the professors uses two numbers in a cell during the BEECH method that are not the only two numbers that can go in that cell. For me to form a chain, the numbers in a cell should only be the two numbers that will go in that cell. I would like to see how the professor gets to the stuck point and why he puts certain numbers in a cell and not others. It is very confusing when I don’t see the logic of cell numbers and then using them to find a chain. Thanks, Robert Jordan