It is a good youtube show.
In mathematics, a percentage is a number or ratio as a fraction of 100. It is often denoted using the percent sign, “%”, or the abbreviation “pct.” For example, 45% (read as “forty-five percent”) is equal to 45/100, or 0.45. The word 'percent' means 'out of 100' or 'per 100'.
Mathematically speaking this presentation is WRONG.
10 is not 10%.
10+10 is not 20%
10+10+10 is not 30%
10+10+10+10 is not 40%
10+10+10+10+10 is not 50%
....
10+10+10+10+10+10+10+10+10+10 is not 100%
JJJJJJJJJJ is not 100%