What I meant was, rapidshare gave up on captcha, cause it wasn't cost-effective. Instead they chose to cut free download speed and slot numbers while they don't care anymore whether download is manual or automated using such programs as JDownloader. I think so will do Zippyshare and others after more or less lengthy "open conflict" state, until they come to the same conclusion.
If I understand the situation with Zippyshare right, they seem to be watching JDownloader's development and update their site once the plugin is updated so it can't work. It's the same as Rapidshare, when they had their Captcha Crusade a while ago. They will need money to pay people to do their job, at the same time when JDownloader and plugin developers here aren't working to get paid, and that's why they (hoster) don't stand a chance
The problem with unofficial plugins was always relatively small user base, is it worth doing it for just a small group of users? Once their number becomes large enough, Zippyshare (or whatever other sharing host) will become aware of the plugin existence and will try to do their best again, same as with official plugin. What will happen then: either the development stops or moves to escape from their attention, what will mean temporary victory for the hoster, or it tires to keep up with hoster updates, that's where they'll start to realize how expensive war for themselves they've started. I'm not sure at all, that some imaginary increase of ads display would cover these expenses.