Follow these steps to recover lost photos and videos from Android on Mac
First: Don't take any new photos or copy anything new to your Android phone.
Second download a program called Android Data Recovery and install it.
Plug your phone it using USB transfer mode (Not Kies or MTP), this is found in settings.
Third once you can see the phones HDD as a removable HDD in Mac explorer (i.e. drivers have finished installing) Start up recuva. Be sure to restore to a different HDD. E.G. restore to C:, NOT your phone!