so it's funny now or..?
i was giving context and the original video
I don't think normal people get their jollies from kids screaming in pain from an accident.
the video has been up since 2010 and has been spread in tons of places with a bunch of reuploads (i had to look for around 5 minutes to find the original), and with the minimal amounts of dislikes, i'm thinking most people enjoy it. actually most of the comments of the video i linked is making fun of what happens. people laugh all the time at others getting hurt or dying from some stupid accident, and i don't think this is any different really.
the slide video is hilarious because nobody had any control over it and the kid probably wasnt hurt too bad
the punch to the face is just pain.
i doubt it was fun for anyone there involved at the time, and that punch was obviously painful. but the video was uploaded by them at some point so that means that they thought it was funny at least. i'm just assuming here but i'd say it's a possibility that the video was uploaded because they laughed at the time when they accidentally punched their friend really hard in the face.
again, stuff like this is laughed at all the time, even when it isn't uploaded for humor. someone can accidentally shoot themselves in the foot or fall down really hard and it would still get laughs from people.