How to start mp4 at half time

Hi guys
I try to play my mp4 file through nginx in windows server 2003.
I nstall and config the nginx in my server and start it, after start nginx I copy my mp4 video to the nginx root directory and when I type the 127.0.0.1/sample.mp4?start=0 in the browser can be download this video from the server and if I set this address to my flash video player I can play it in the video player. (I made flash video player in flash CS5 and actionscript3 and I don't use jwplayer or flowplayer)

Now I need too seek this video into 300.3 befor video completely downloaded , for this case I type http://127.0.0.1/sample.mp4?start=300.3 in the browser but I get the video from the 0 time not 300.3 time.

My sample video have metadata at the begening the file.
Note: when I try to get the seekpoints from the metadata in filash video player for point 300 I give 300.3 and for point 200 I give 200.2

Now I set this numbers opposite the start in the address bar But flash video player start this video from 0 time...!!!

http://127.0.0.1/sample.mp4?start=300.3
Or
http://127.0.0.1/sample.mp4?start=200.3

I have --with-http_mp4_module in the nginx when I list the nginx modules. (nginx -V).

If you think my problem becuss of metadata please tips me to moov atoms from last of file to begening.

please advice me.
many thanks