11.04 Adobe (Flash) issue persists.

I don't know if this would help but you can try using the flash-aid addon for Firefox:

https://addons.mozilla.org/en-us/firefox/addon/flash-aid/

HTH.

I have Flash Aid, and it certainly does something but I think it causes more issues than it solves in my case; everytime I try it the problem still remains.

Although it might be unrelated I'd purge the transitional package flashplugin-nonfree.
While running flash videos try right click -> (adobe) preferences -> tick hardware acceleration support.

Adobe context menu incl. some other tools, such as 'show video info', for example shows software or hardware rendering.

I would if I could, but the video's don't even load I just receive the crash page/grey screen.

Was Firefox 4.0 installed via official repositories or did you install it from other sources before upgrading to Natty, or was Natty a fresh installation?

Is it correct that you run a 32bit installation on an AMD pc?

Try to purge and reinstall flashplugin-installer.
Reminder, during any procedure regarding Firefox configuration (if possible also during retrieve of updates), Firefox should be closed.
Open a terminal: ctrl+alt+t
sudo apt-get purge flashplugin-installer
sudo apt-get clean
sudo apt-get autoclean
sudo apt-get autoremove

sudo apt-get install flashplugin-installer

If the issue isn't solved backup your Firefox profile and restart with a clean one.
In any case bookmarks and else can be reimported successive from backup folder in order to find for example a broken extension.
mv ~/.mozilla mozilla-backup

## 'mozilla-backup' is an unhidden directory now which can be found in your /home/user.

Restart Firefox.

I installed Firefox 4.0 from official repositories, it upgraded after downloading an Ubuntu update.

I do have the 32bit installation on an AMD PC.

I tried both of the above steps, and while it did give me back the default homepage flash players till crashes when I try to play videos.

Since crashes are reproducable consider to report a bug incl. steps on how to trigger the crash.
https://help.ubuntu.com/community/ReportingBugs

It doesn't crash though otherwise I would, it's stable just no video works.

Since you wrote
> till crashes when I try to play videos

it sounded that it does still crash.

> just no video works

Javascript is enabled?
What do you see instead when a video 'isn't working'?
If possible take a screenshot, upload to your favourite host and post the linke here.

Sorry, I was referring to the fact that Firefox doesn't crash.

As for what happens the video's start to load, then a grey screen appears declaring that Adobe Flash Plug-in has crashed and that there is no report available. Underneath is an option to reload the page, and that is all.

> declaring that Adobe Flash Plug-in has crashed

Right after flashplugin crashes report a bug via apport.

I will try, however the steps listed in your above link do not work, as after typing in the required commands into run app window nothing happens.