Blood
About
On October 9th, 2006, Mark Garza of Zapato, TX uploaded "Blood": a family home video in his son struggles with pronouncing the word "blood", to which Mark laughs. The child continues to get upset telling his father, "Not Funny" which of course, makes him laugh harder.
Today the video has over 15 million views, and is one of the most popular videos of it's kind on Youtube, often linked to by referrals from "Charlie bit my finger" and "when a three year old is asked about monsters."
The video is available on Youtube but embedding has been disabled.
https://www.youtube.com/watch?v=-fVDGu82FeQ
The long version of the video puts the scene in context. We see the toddler horsing around, too close to the baby, pretending to be a monster, and accidentally causing a bloody lip. The parents notice the blood right away but the toddler continues to play, oblivious to his accident. It is only after a few minutes that he sees the blood, and is shocked by what he percieves as an apparent lack of concern from his parents who have already addressed the situation.
The video can be viewed on Youtube, but embedding on this one has also been disabled.
https://www.youtube.com/watch?v=YZ0LxAZazzY
As for the spread, it's a simple case of the Bandwagon Effect: once the video became popular, others were compelled to create videos emulating it.
Overlooked?
Incidentally, there is an unexpected absense of interviews. It doesn't appear that Mark Garza has made any attempt to capitalize on the viral traffic of the clip.