Unexpected file format when trying to open a .fla file

I am trying to customize a video player skin from f4player (http://code.google.com/p/f4player/downloads/detail?name=f4player-beta-v1.00.zip [the file is mySkin.fla]).

I am using flash cs3 pro and I get the error "Unexpected file form开发者_开发问答at" when trying to open the file, a friend has flash cs4 and has the same error.

Is there something I could do to open this .fla file correctly?

Or maybe if someone could try opening it and saving it again for cs3?

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It's a Flash CS5 document, so you need Flash CS5 (or 5.5) to edit it. You could download a trial version from adobe.com.