YOU NEED TO HAVE GOOGLE CHROME FOR THIS.
4-On 'Show Package Contents', follow Contents>Resources>Flash Player.plugin
5-Move the file named "Flash Player.plugin" to the trash, as it has been corrupted. But keep that window open.
6-Now go to Spotlight (the magnifying glass in the top-right of your screen)
7-Type "Flash Player.plugin" into Spotlight and once you have the results, select "Show All In Finder"
8-A new Finder window will open and you need to find the file called "Flash Player.plugin" which is in a folder called "Internet Plug-ins". You can use "Open Enclosing Folder" for this.
9-If you have found the file, skip this step. If not, you need to download Google Chrome and try again.
10-Now you have the file, make a duplicate of it. Drag the duplicate into the window you kept open in step 2. Make sure the file name is just "Flash Player.plugin".
11-Close all windows and go back to the file which you originally used 'Show Package Contents' on. Double-click it and it should now work! Good luck!