Lighttpd

Hi!
I want to know if is possible to stream a video (flv or mp4) using X-sendfile header.
I want to do some checking with php before sending the file, and there's no problem streaming the file from start, but when I try to stream the video from a specific position (for the JW Player) I just can't find the way to do it.
I made a rewrite command on the server, so when a file is retrieved and an id is passed, a php is executed, passing by the file unique id and the start GET variable sent by the JW Player. I couldn't find a way to do it with the x-lighttpd-send-file header, so I tried with x-sendfile2 using the range parameters. The file is streamed from that position when I download it directly, but the file is corrupted or something, because I can't play it with any media player. The JW Player shows an error (file not found or access denied) and stops playing.

Any ideas?
I'm using a Debian Lenny, Lighttpd 1.4.28 installed from source, mod_h264_straming 2.2.9, and JW Player 4.5.

Thank you!