You can update these links manually to point to a photo on your HD if you really want to.
Use File > Database Browser > aircraft drop-down tab and search for your aircraft using IN field AR (aircraft registration). Look at LK1 and LK2 - these are the web links to the big photos. You can edit these fields using the buttons Edit/Delete/Add at the bottom. Delete deletes the whole data line, so be careful :-)
There are 3rd party SQL database editors if you are going to do a lot of editing.