Flash Player version 10.1.102.64 is the last version available to PPC Mac users. However, this Flash version won't work for many videos on Facebook, YouTube and other sites. Adobe's latest version, 10.2.x or later, is only for Intel Macs. Adobe will not provide a newer Flash version for PPC Macs.
The message requesting that you download Adobe Flash Player takes you to Flash Player requiring an Intel processor. Doesn't work on a PowerPC processor. I found a hack, installed it & it works with Firefox, TenFourFox & Safari.
Download this http://www.steelbin.com/FPforFBPPC.zip to your desktop, unzip it, and replace the current Flash Player plug-in which is in your main/Library/Internet Plug-Ins folder, (not the user Library). Save the old one just in case this one doesn't work.
Hack Allows PowerPC Macs to Access Flash 11 Content