I have been seeing this term quite often.
Contrary to what I thought, the term means ‘comes from the term “Viral Marketing” which is said to have been originated by Tim Draper and Jeffrey Rayport to explain the popularity of a product spreading like a virus. Which aptly describes YouTube, by far the most dominant video viewing service in the world.
You can read more about this subject and the top YouTube viral videos here.
The fastest trending viral brand is YouTube. Created in 2005 by Chad Hurley, Steve Chen, and Jawed Karim and acquired by Google in 2006, YouTube grew to become the second-most used search engine in the world, parent-company Google being the biggest search engine.