See here for instructions to enable Flash in Fennec:

http://www.nokiaphoneblog.com/2010/0...bile-1-0-n900/

(It's disabled by default because it causes bad performance problems on some sites.)

By the way, you can also get Firefox 6.0 "Aurora" builds from here:

http://ftp.mozilla.org/pub/mozilla.o...ra-maemo5-gtk/

and Firefox 7.0 "Nightly" builds from here:

http://ftp.mozilla.org/pub/mozilla.o...al-maemo5-gtk/

For more information about the Beta/Aurora/Nightly channels, see http://blog.mozilla.com/blog/2011/04...apid-releases/