I disagree. You can always better yourself in everything. Learning from books, videos and other sources works in every other field, why should it not in sex?

Its the same as with everthing else on the internet (and of the internet for that matter) you have to always think critically, even if the content is wrong you can still learn. If you listen to Fox News for example you can learn alot about what technics the media uses, because Fox uses them totally obviously.