yes i told that i don't know why 6000 and 10000 but this work.
What in problem you don't understand??? 
Open
http://master255.no-ip.org/?file=/res/Музыка/B/Benny Benassi/Benny Benassi - Cinema (featuring Gary Go).flac
click on end of buffered or end of seek line and js return error. Becouse function searchTimestamp return number (index) more than necessary. Becouse algorithm in this function wrong!! He return 19 index when seeking points 18 (all points). You can repeat this problem on your server. Download https://github.com/master255/Media-Library  and repeat this. This all simple. That is not yet understood???