There is a back door way to get the original image. Safe the document as an html web page file:
Click File > Save As > Under save as type: choose "Web Page (*.htm; *.html)
Remember the folder you save the file to.
Go to the folder you saved the new file to and you will see a sub-folder with the same name as the file you just created. Inside this subfolder are all the images your document contains.
Note: you may see two of the same image in this new subfolder. The reason for this is that the original picture was modified after it was inserted into the Word document, so Word will extract both the original picture and the modified version of the picture that would appear in print. An example of a modification would be if the picture were shrunken to fit or converted to grayscale.