TV advertisers are finally discovering that YouTube + viral imagination = free media.

The good news for you is that money is not a barrier, which means that marketers of any size can play. But the rules are different, as they always are online.

Because media is free but attention is not (this is flipped from TV world) you need to make a different sort of ad for a different sort of audience.

1. Assume that the viewer has the attention span of an espresso-crazed fruitfly. That means slapstick, quick cuts and velocity.

2. Find a word or phrase that you can own in Google, that fits in an email, and that comes up in discussion at the cafeteria table or in the playground.

Castrol gets both rules right in this inane commercial.

3. Length doesn't matter. 10 seconds is fine and so is five minutes. Media is free, remember?

4. Challenge the status quo, be provocative, touch a social nerve or create some other sort of interesting conversation. In other words, a commercial worth watching.

Dove does both in this now-famous commercial.

Because of the power of free media, I expect to see a whole host of commercials that would never be deemed effective enough to spend big media money on, but that generate huge views online. Look for plenty of irrelevant slogans and catch phrases and off strategy content... anything for an eyeball.

Also, understand that this is out of your control. Once launched, what happens, happens. One commercial I know of caught fire and ended up with millions of views. The client then called the producer, screaming in anger. He wanted to be able to turn it off, to decide how it got used, who talked about it, etc. You can't. Once it spreads, it belongs to the community, not to you.

The biggest shift is going to be that organizations that could never have afforded a national campaign will suddenly have one. The same way that there's very little correlation between popular websites and big companies, we'll see that the most popular commercials get done by little shops that have nothing to lose.