Is this because the flv player(s) are so ... crappy... for lack of a really descriptive word?
I went through six or maybe more of the usual run-of-the-mill flv players before one of my good buddies pointed me to this flv player.
It's called, nFLVPlayer and you can get it here:
http://www.zeraha.org/
As the author states, he needed something decent and it wasn't available, so he wrote one that was. That type of situation usually leads to a good product.