I have seen lots of youtube videos which has confused me a lot and it looks like all of them are lying, I have not seen anybody before and after the experience.
What is the best treatment which has actually worked for alopecia aerate
Wikipedia suggests that there are no known reliable and safe treatments. Corticosteroids have been used but evidence for efficacy is weak. The US FDA has allowed breakthrough use of at least one drug that is ordinarily prescribed for rheumatoid arthritis following early trial successes, with a phase 3 trial ongoing, but there is no FDA-approved treatment.
In general as a rule there is a lot more financial (and other) incentive to say there is a magic cure for something, and almost no incentive to say there is not. Even if someone provides before and after "evidence", this is not reliable unless it is coming from a reputable source (such as a scientific article in a reputable journal, a trusted government regulatory agency or public health institute, etc). For a simple example, you could take an "after" photo, remove some hair and take a "before" photo, and claim whatever treatment you want worked.