Movie trailer in swf

hi all:)
i want something like ( click whatever video inside and watch the exsample)
a movie trailer with preloader and play before part of preloader
(not waiting buffering until 100% loaded)
should i convert media file to flv.?

do u know wha i mean?:stuck_out_tongue:
any tutorials or forums? plx help me out:d:
thank u so much

w/ luv