What's he using to play Flash?

I just subscribed to a digital version of Sky and Telescope. Needs Flash. I have
flash, but the mag told me I didn't. I happened to be using Firefox ESR. 10.7

Switched to Iron (Chrome derivative browser which does its own flash,) and
magazine opened. Opera also opened it.

I've had the same problem with FX on Windows XP. Could be the ESR version.

I'm using 11.04. Any upgrades will have to wait until after holidays.
I'm too busy to deal with Ubuntu right now. FX ESR only gets security updates -
no other "improvements"