Here are some of my suggestions
It wasn't until I joined my school's video production club, which made me realize I can work in the film industry and someday write or direct great films.
It wasn't until I joined my school's video production club that
I realized my potentials in the film industry...
I would try to rewrite the first two sentences, and somehow combine them into just one. Also try not to start a sentence with "but". Maybe it could be like this. "Knowing the difficulties of establishing..., however, has made me doubt..."
Also try to work on the conclusion/last sentence. The club has given you the confidence to embark on this career path. You're not, I assume, ready to "enter the industry" yet. If you were, you wouldn't be applying for college now.
That's what I think, and good luck to wherever you're applying too :)