Charlie bit me, with 67 MILLION views, is an example of a classic viral video
Numa Numa with 23 MILLION views is another example
When users start making their own versions of videos that's viral!
On the commercial side, I believe this Honda Choir video went viral.
I can think of many other examples. These were top of mind.
To me, when a company (or the ad company they hired) has to announce that they have just created a viral video, it isn't. Viral videos are, unexpected, engaging, and memorable; and they become popular because viewers say they are - not the producers or the companies that hire them.
That said, I did not think the Lotus Foundations video was that bad. I laughed. I would have laughed more if it was not promoted by IBM as being viral. By telling me the video was viral before I watched it, they set themselves up for more critical review.
Here's an example of something my wife received unexpectedly and one that she immediately forwarded to others (viral behavior?). I think it will probably become quite popular. As a potentially viral marketing video, I think it's effective in that it got me thinking about the company's product even though the video was about my wife.
In my opinion, whether the above goes viral or not will depend on what the viewers think, not the creators or vendor.
What do YOU think?