It's a joke on every cycling internet forum, and one of the constant problems we see in the Fit Studio. Why is Saddle Height so difficult to get right?
If you think your saddle is too high, lower it! Try 1cm lower. Feel better? Try 2cm lower. Still feel better? Okay, now we know your position is way off, and you need to see a professional fitter because your change in saddle height is also effecting your fore/aft position which is also important.
Let's look at some stills from the video. You see in the first picture that the knee is over-extended. Or perhaps you don't see that because it's not wildly extended, it's just too much. I use this as an example precisely because it's not extreme - there is some bend in the knee at the bottom of the pedal stroke, but he was still over-extended and it was costing him a loss of power as well as saddle discomfort. Also note his foot angle. Again, pointed but nothing compared to what we some times see.
Now let's look at the correct extension for this athlete. You see he's extending approx 10 degrees less after lowering his saddle height, and you'll also notice his heel has dropped a little over 4 degrees. This helps us realize that, in fact, his saddle was too high and he was reaching at the bottom of his pedal stroke. It should be noted that the athlete shown here reported a significant increase in power output after his fit session.
So, what can we learn from this? Easy...make sure your saddle isn't too high! As stated above, take some video of yourself. If you think you may be over-extended, try lowering your saddle a bit and feel the effects. I would caution, however, that if you're used to a saddle that's extremely high, it can be a bit of a process to get you down to the correct saddle height because it's possible you've developed some bad pedal stroke habits.