I originally reported this at http://www.reddit.com/r/bugs/comments/vlgfu/mouse_wheel_scrolling_broken_in_firefox_after/
Three months later, using Firefox 15, the issue is still there. I'm experiencing it on multiple computers. Creating a new profile (so no add-ons are enabled) doesn't fix it either.
Switching to a different tab and then switching back makes scrolling work again.
I'm not able to reproduce this behavior on Firefox 15.0.1 on Ubuntu. Are you using Mac, Windows, or something else? Does it happen in chrome or IE as well?
Flash objects tend to take control of the mouse away from the browser. Clicking elsewhere on the page is something that often works for me on other sites when I have similar problems.
I'm using Windows 7 on all computers. It doesn't happen in Chrome or IE.
Clicking elsewhere doesn't help, I can select text, scroll with they keyboard arrows, but still the mouse scroll won't work.