FLV video not starting

I’m experimenting FLV plugin for a WordPress site: http://www.lucianagallo.com/blog/.
I have the video on site: http://www.lucianagallo.com/images/intevista.mp4
This address is used into a provisional post I’m preparing, simply reporting this: [flv:/images/intervista.mp4 640 360]
The post is unfortunately not visible and has not been pubblished yet, because it’s not working. I put a jpg image in the same directory and it shows regularly at start, but when I click the start video button I always must do it two times, then it begins to “roll” as waiting for the start, but never reaches a conclusion.
It looks as a block from the server, or something. Do you have any idea? Thanks.