Take a look at the billboard above and then think about the slogan "Fuck the Corporate Media." Think about how much less effective the attack on this billboard would have been if the jammers had merely blacked out this guy's teeth, or if they had tried to destroy the sign, or if they had put a tarp over the sign.
Spitting and swearing and trying to cover their camera lenses is the same as trying to throw a tarp over a billboard. Be angry, but be creative too.
Here's my attempt at creativity:
Make a few signs that you want on camera, and then follow the reporters around the event. With a little cooperation you might be able to get ten friends to help out, each one of you holding the exact same sign up, hoping to end up in almost every shot the media people get.
The signs might say something lke "corporate media=propaganda machine" and the signs might include a webpage address where you've set up a list of articles and thoughts about the corporate media, the war, etc...
If you are asked by a reporter to say a few comments about why you come out for protests, answer by spouting out the webpage address you've created, and then try to explain why you think the corporate media is part of the problem. Hold up your sign. Make a hundred paper signs and pass them out to people at the next rally. Ask people to tape the signs to their chests and surround the cameras.
That's just one idea. I'd love to hear other people's creative ideas.
There has to be more than one alternative. Has to be a better way to disrupt the corporate media system than swearing and mooning and spitting. And there is no reason to keep using a tactic that's doing us harm instead of them.