I agree with Andre and utcenter. If you only know enough to narrowly pass a certification test then it doesn't really prove you know anything but how to pass a test. The entire point of certification is to certify that you have an certain level of knowledge in a given topic. If you learn Qt, and practice developing with it, then you will easily pass the exam. If you can't pass the exam, then you haven't the knowledge you need to be certified.
So, in short: use the videos, use the books, use the forums, use the documentation... and code, code, code.