It's an ongoing drama: Flash player on PowerPC systems - you can either choose to ignore flash at all (no mozilla plugin installed) or the a non-working version of Gnash installed, which gives you no output of YouTube videos and hanging, CPU eating processes:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
16302 ij 20 0 63964 22m 13m R 75.0 2.2 4:27.56 gtk-gnash
16308 ij 20 0 44792 13m 10m S 5.9 1.3 0:24.46 gtk-gnash
16297 ij 20 0 54172 14m 10m R 2.6 1.4 0:11.07 gtk-gnash
16301 ij 20 0 54172 14m 10m S 2.6 1.4 0:10.92 gtk-gnash
I really doubt that there will ever be a working Flash player for non-Intel compatible architectures. :-(
I'll try swf-player next, but have little hope that it will be better than cr^H^Hgnash....
swfdec-mozilla doesn't work properly either. It hangs iceweasel just a second after playing a YouTube video and the picture is broken.