Actually, it's quite easy to detect AdBlock or similar browsers/addons/etc. I'm a freelance coder, and this is a frequent request from clients.There are so kany dufferent types of adblick you can use that would be virtually impossible. Also, like you have stated, tons use it so youtube would get a massive backlash most likely. Im sorry to hear that the $ you should have earned has beentaken by those who cant watch a 30 second ad. Although they are annoying, ads are needed and people do depend on them.