Hi Antonio,
jPlayer is designed for html 5 and only uses Flash as a fallback mechanism so trying to force Flash is working against what it was intended for. iPad users for example won't be able to view it using Flash.
Using Flash also does not really secure the video or audio, a user could view the source of the page and get the real urls for the media and download it directly. So it seems kind of pointless to try to do that.
Best,
Joe