This is how to go about reactivating the paid MPEG4:

Within Movie Edit Pro, with the internet connection active, click "Help" - "Activate additional functions" - "Activate MPEG4" and the activation dialog will open. Click on "Restore activation" and you will be able to retrieve your computer's ID code by clicking the "Post/Fax" option in the activation dialog. You can then copy and paste this code into the proper place in the Magix browser window that opens upon clicking the restore activation function. You would also enter in your purchase/order number for when you originally bought the MPEG4 codec.

Here is how to go about (re)activating the MPEG2 codec:

Within Movie Edit Pro, with the internet connection active, click "Help" - "Activate additional functions" - "Activate MPEG2" and choose the online function. You will have to enter in your registration information at this point, then the MPEG2 activation code will be emailed to you. You can then copy and paste this code into the MPEG2 activation dialog when prompted to do so.