The new 10.1 adobe flash is 32 bit only and using nspluginwrapper is a crap shoot, it may work but most times not, so I went back to www-plugins/adobe-flash-10.0.45.2-r1 and it works fine. It was removed because of security concerns. Sometimes I do need flash to play a video, wish it was not true but it is. here is what I did.

echo ">=www-plugins/adobe-flash-10.1.53.64" >> /etc/portage/package.mask
echo "=www-plugins/adobe-flash-10.0.45.2-r1" /
>> /etc/portage/package.unmask
emerge -av www-plugins/adobe-flash