You don’t extract it. If the file says wdtvliveplus_1.04.31_B, change it to wdtvliveplus_1.07.31_B which would be higher than the one you have installed. Once loaded it will show the correct FW installed. 1.04.31_B.
This is incorrect. I was thinking of another FW Rollback. The post below is correct.
Sorry for the confusion.