Can you really learn bass guitar online?
In this video Paul Wolfe looks at the question and suggests lots of very good reason why you can in fact learn bass guitar online.
I think that the most important thing for any bass player to do is to take bass lessons of some description. Online or offline just having lessons will help you to improve and advance as a bass player.
There are plenty of video lessons on the Internet for you to watch and learn from. The problem with just using free recourses like that is that you have no structure to follow. No one to guide you which things you should be learning and in which order. That is why I believe that taking bass lessons is the only way forward for someone who is serious about learning to play their bass guitar.