I've shot many digital shorts. The ones below are a few that truly "went viral", meaning in the millions or at least the 100's of thousands (across multiple sites and youtube accounts).
DAVID BLAINE STREET MAGIC PART 2 30 Million+ Views
OBAMA-MCCAIN DANCE-OFF 20 Million+ Views
SNEEZING GIRL/BLESS YOU BOY
This is from an actual "Today Show" story on a girl who couldn't stop sneezing. I put the boy into the it. Although I shot it for "Jimmy Kimmel Live", it's on this page because it became surprisingly viral online.