Downgrade is possible via:http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_14266&sliceId=2
However, I strongly urge anyone NOT to do so unless you are very sure what you are doing and why you need to use a older version of Flash (prior to v10).
The reason? See this:
which doesn't really say much. The keyword however, is "Clickjacking".
Read more at:
Anyway, back to downgrading of Flash. Its a very big download because they had archive all possible version of that particular branch into the zip file which you can download at the first link. For example, Flash 9 is 139MB (as of now).
Well, I am downgrading Flash (for a while at least) for a particular reason. That reason will be obvious in the next few posts in the future.