One of the little known secrets of the current online video craze is the dark clouds on the horizon for anyone in the corporate reputation management business. If you work at a company or an agency and have anything whatsoever to do with helping your company or client manage and maintain their image or reputation, you really should start paying attention to how vulnerable your brand is to online video attacks.

Brand activists — and I don’t just mean the one off disgruntled consumer types — are starting to understand how easy it is to catch companies off-guard and produce low-cost negative videos to make their positions known in creative, new ways. Just ask the folks at companies like McDonald’s and ExxonMobil what it’s like to deal everyday now with negative viral videos like “Toast the Earth with ExxonMobil.”

Of course, we all know since the early days of JibJab’s classic “This Land” political cartoon that anyone and everyone could be a target. Now, however, the playing field has changed in a big way, and for a couple of very important reasons.

For one, the YouTube generation has figured out that you don’t need a big budget and fancy interactive shop to let loose your frustrations. Any cheap camcorder and cell phone will do. And even more important and challenging for brands though is the fact that how people search and see online video is all about to change. Currently, if you want to see how activists are bashing your brand, you need to swing by all of the big video portals, like YouTube or Yahoo Video, to get a sense of what’s out there. Most consumers aren’t doing that today so some brands feel safe from large numbers of eyeballs at the moment — but just wait. The tidal wave of change is coming.

As Google, Yahoo, MSN, and AOL move to integrate video search across their main search engines, the visibility of this growing catalog of work will explode around many companies. Over the next few years, video results will start showing up more and more among the top rankings when people go looking for your brand. Companies need to start mapping out their action plans now for how to combat this new media tactic. If you don’t start thinking about it now, you surely will when the CEO calls.