justa - 11:10 am on Jan 5, 2011 (gmt 0)

If you're using JW Player you just need to specify a value in the flashvars.

start ( 0 )

From the website
Position in seconds where playback should start. This option works for HTTP Pseudostreaming, RTMP Streaming and the MP3 and Youtube files. It does not work for regular videos.

Unless your server has streaming capabilities then this won't work for you.

There's information on the JW site about this,
JW HTTP Sudostreaming [longtailvideo.com]
Apache Module Sudostreaming [h264.code-shop.com]