After exausting tests I came to the conclusion that the FLV gets stuck in BUFFERING state and never enter play state...
I re-highlight that it works perfectly using older plug-in.
In practice if this was a project created and working and approved 2 years ago... it would have stopped working with the player update!
It is something to do with the way the FLVPlayback component enters the playing state.
And to add the the confusion in some loads I have randomly seen it working fine!!!
May seen linked to the version in cache and speed of the connection.
Any help kindly on where to look for a solution?