Everybody trying to help me. Everybody is cool.

There is nothing wrong with the sentences but they can be better framed. I don;t understand why you are talking in the third person (Nahid's too) and then speaking in the first person (I have watched it ... ) A. My favorite film is "Mr. Nice Guy" starring Jackie Chan B. Mine too. I have watched it many times. (If you are Nahid) or B. Nahid's too. He has watched it many times (If Nahid is a third person) Nahid's = Belonging to Nahid. When we want to show that something belongs to somebody or something, we usually add 's to a singular noun and an apostrophe ' to a plural noun, for example: the boy's ball (one boy) the boys' ball (two or more boys) Notice that the number of balls does not matter. The structure is influenced by the possessor and not the possessed. See this website to have a deeper understanding : http://www.englishclub.com/grammar/nouns-possessive.htm

Kobir: I have a favorite movie that is "Mr. Nice Guy" by Jackie Chan. Kobir: My favorite movie is "Mr. Nice Guy" with Jackie Chan. > My favorite movie... is more common. > Use "with" because Jackie Chan is the actor, not the director or writer. Me: Nahid's favorite movie too. I watched that many times. Me: It is my favorite movie, too. > Missing subject and verb > Use my instead of Nahid's. Talking about yourself in the third person is very strange in English. I've watched it many times. > Verb should be in present perfect: have+past participle (See: http://www.englishpage.com/verbpage/presentperfect.html) > Also, use "it" or "that movie," but not just "that." The 's of Nahid's shows possession. > Nahid's house, Nahid's friend, Nahid's job, Nahid's favorite movie

Nothing wrong with it. It means the favourite film 'of Nahid'.