Well it is because they will be "stealing" the video count from the original uploader.
EG: If Fah (imagine that you are a company owner and a Youtube Partner) uploads the ORIGINAL SNSD video on Monday and on Tuesday 100 random people uploads a SNSD music video (which has been downloaded thanks for Fah's video), Fah will be losing lots of video counts as those 100 people will be gaining views.
Summary: If you are the only one, you will be gaining the "monopoly power". Each view counts towards every penny.
Agree, yea, no?