I didn't have any problems with flash (ie youtube) since Fedora 9 was released. This morning I installed some packages. Going back to bash history it's:
ipod-sharp ipod-sharp-devel libipoddevicelibipoddevice-devel smb4k devedelibdvdcss libdvdread libdvdnav lsdvd libdvbpsi

Then I switched off my computer and went out to a party (a good one, btw).
I just came back home and got an email with some link to youtube and it says:
This is strange,isn't it?
I tried to install flash again, but it says that it's already installed. I did not tamper with any config files. The only thing I did today was installing the above mentioned packages.

any hints. thanks

Reinstalling libflashsupport has resolved the problem.
cheers