VLC was my preferred player in Windows, and still remains my default in OS X. There is nary a format which the orange pylon cannot handle. Thanks to the VLC and FFMPEG guys for all the hard work!
Some encoders might not create the index properly, and some players might have tricks to seek (offline?) even without one.
To repair these files, see: http://muzso.hu/2008/12/18/fixing-flash-videos-flv-for-use-w...