He's saying its normal to slightly overcompensate when fixing something
that was towards being way to extreme on one variable, like how you were
way zoomed in so to fix it you zoomed out a lot and overshot it a bit, but
didn't notice it because to you it looked better since it was technically
better than what you started with. Don't know what you would really
call this effect on the mind though.

As for the 10 seconds I have no idea why it would be a bad thing, doesn't
upset me at all that you have a bit of a black screen at the end while the music ends.

Also I saw some people saying they didn't like the sound effect at the end, but
while it was a tad bit strange I kind of like it, call me odd for it if you will.