can kung fu be self taught

hmmm well maybe through experience it can be. but it won't be kung fu. Kung fu is a style, so your self invented style won't be exactly the same. It will be more closer to american boxing.

It's better for you to study at a school. Sure you can learn a few moves from books and tapes but you miss out on the philosophies and disciplines that comes with the art. Also, you have more support and encouragement in a school compared to being self-taught. Trust me, conditioning for 3 hours everyday will become boring, and you will lose your drive unless you have a group behind you pushing you to go forward. In kung fu there's sparing (practical stuff) and there's forms (flashy choreography).

I've seen have a couple of self taught people try to compete at tournaments. They try to execute moves and don't know how to follow up, so they start brawling and become easy to read. Then one of the sifus pats him on the back and hands him a business card.

Like most refined arts (that have really taken a long time to be perfected), you are better off learning from an expert. It might be possible for you to learn on your own, but I imagine it would be painstakingly difficult ~ whereas if you were being taught directly by an expert, the process of learning could not only be much simpler, but you might grasp the concepts and nail them down properly a lot quicker as well.

You can teach yourself the forms by following videos,but for the application and the correct forms you'll need a teacher.So,you can copy the moves but you wouldn't know if it's correct or not.That's where you need a teacher.