Change of frame rate without changing speed

hi everyone!

i’m pretty new to flash and have a probably very basic question.

i got a flash video file with a bunch of layers that has been created with 25 fps.

the web site i need to upload the video to requires 18 fps.

when i change the frame rate in the .fla file and play the movie, it slows down. (the total amount of seconds increase)

is there a way to change the frame rate played at the same speed without having the movie slow down?

i’d appreciate every bit of information.

thanks!