If you download Firefox there are two add ons you can download to help prevent unwanted flash.

Ad Block Plus and Flashblock.

Ad Block will allow you to block all advertiser (including the advertisers domain name to keep any picture based advertisements from loading.)

and Flash Block will stop all flash from loading and give you an easy way to remove the flash content. You can also white list sites to displace flash automatically such as YouTube.

Both are wonderful add ons!