What to do when the correct answer to a question changes over time?
I was looking at a question (regarding downloading youtube videos), the accepted answer, I called the attention of the author to this fact... but he said: "Yeah, this answer is quite old. I wouldn't be surprised if the method has changed."
I thought one of the purposes of StackOverflow is to endeavour to have up-to-date answers to its questions (so when we find them from a Google search they work!). How are these updated in practice? What incentives are there to update a question/answer?
It seems unfair remove the 15 points the answerer received but un-accepting the (previously correct) answer... is this the only thing that can be done?