No matter how funny, good, intelligent or rare a video/picture/post is, there will always be someone disliking it, and if it's only for the sake of preventing a 'perfect' voting. Also, downvotes arise from jealousy, hate or any other form of secret respect.
person 1: dude check out this video, its a child doing a backflip while making pancakeson the back of an elephant.
person 2: wow thats incredible. *obligatory downvote*
person 1: i cant believe there is actually nobody that dislikes this newsfeed. well, its about a migrated disabled kid that survived cancer and the war.
A downvoter is someone who will go on UD and downvote everything they come across because they have no skill to make their own definitions and have no friends to help them so to make them feel better about themselves they just try and ruin everyone elses fun.
I went on my user page today and sure enuf every single on my definitions had a single downvote on them. I kinda feel sorry for the downvoter because if they think it will really hurt someones feelings or that the person really gives a shit what they think is sad. They should just buy a print dictionary and torture it instead.