Here the result with option-c:
md5sum -c livedvd-amd64-multilib-20121221.iso
md5sum: DVD-hybrid-amd64-blue.png: No such file or directory
DVD-hybrid-amd64-blue.png: FAILED open or read
md5sum: DVD-hybrid-amd64-purple.png: No such file or directory
DVD-hybrid-amd64-purple.png: FAILED open or read
md5sum: DVD-hybrid-x86-amd64-blue.png: No such file or directory
DVD-hybrid-x86-amd64-blue.png: FAILED open or read
md5sum: DVD-hybrid-x86-amd64-purple.png: No such file or directory
DVD-hybrid-x86-amd64-purple.png: FAILED open or read
md5sum: FINAL_4x3_gentoo_ten_Blue-1024-768-final.png: No such file or directory
FINAL_4x3_gentoo_ten_Blue-1024-768-final.png: FAILED open or read
md5sum: FINAL_4x3_gentoo_ten_Purple-1152-864.png: No such file or directory
FINAL_4x3_gentoo_ten_Purple-1152-864.png: FAILED open or read
md5sum: FINAL_4x3_gentoo_ten_Purple-1280-960-final.png: No such file or
directory
FINAL_4x3_gentoo_ten_Purple-1280-960-final.png: FAILED open or read
md5sum: FINAL_4x3_gentoo_ten_Purple-1024-768-final.png: No such file or
directory
FINAL_4x3_gentoo_ten_Purple-1024-768-final.png: FAILED open or read
md5sum: FINAL_4x3_gentoo_ten_Blue-1280-960-final.png: No such file or directory
FINAL_4x3_gentoo_ten_Blue-1280-960-final.png: FAILED open or read
md5sum: FINAL_4x3_gentoo_ten_Blue-1152-864.png: No such file or directory
FINAL_4x3_gentoo_ten_Blue-1152-864.png: FAILED open or read
md5sum: FINAL_4x3_gentoo_ten_Blue-800-600.png: No such file or directory
FINAL_4x3_gentoo_ten_Blue-800-600.png: FAILED open or read
md5sum: FINAL_4x3_gentoo_ten_Purple-800-600.png: No such file or directory
FINAL_4x3_gentoo_ten_Purple-800-600.png: FAILED open or read
md5sum: FINAL_widescreen-Blue-1920-1200-final.png: No such file or directory
FINAL_widescreen-Blue-1920-1200-final.png: FAILED open or read
md5sum: FINAL_widescreen-Blue-1440-900-final.png: No such file or directory
FINAL_widescreen-Blue-1440-900-final.png: FAILED open or read
md5sum: FINAL_widescreen-Blue-1920-1080-final.png: No such file or directory
FINAL_widescreen-Blue-1920-1080-final.png: FAILED open or read
md5sum: FINAL_widescreen-Blue-1600-900-final.png: No such file or directory
FINAL_widescreen-Blue-1600-900-final.png: FAILED open or read
md5sum: FINAL_widescreen-Blue-1280-800-final.png: No such file or directory
FINAL_widescreen-Blue-1280-800-final.png: FAILED open or read
md5sum: FINAL_widescreen-Blue-1280-720-final.png: No such file or directory
FINAL_widescreen-Blue-1280-720-final.png: FAILED open or read
md5sum: FINAL_widescreen-Purple-1920-1080-final.png: No such file or directory
FINAL_widescreen-Purple-1920-1080-final.png: FAILED open or read
md5sum: FINAL_widescreen-Purple-1280-720-final.png: No such file or directory
FINAL_widescreen-Purple-1280-720-final.png: FAILED open or read
md5sum: FINAL_widescreen-Purple-1280-800-final.png: No such file or directory
FINAL_widescreen-Purple-1280-800-final.png: FAILED open or read
md5sum: FINAL_widescreen-Purple-1920-1200-final.png: No such file or directory
FINAL_widescreen-Purple-1920-1200-final.png: FAILED open or read
md5sum: FINAL_widescreen-Purple-1440-900-final.png: No such file or directory
FINAL_widescreen-Purple-1440-900-final.png: FAILED open or read
md5sum: FINAL_widescreen-Purple-1600-900-final.png: No such file or directory
FINAL_widescreen-Purple-1600-900-final.png: FAILED open or read
md5sum: gentoo-flowers-1024.png: No such file or directory
gentoo-flowers-1024.png: FAILED open or read
md5sum: gentoo-flowers-1152.png: No such file or directory
gentoo-flowers-1152.png: FAILED open or read
md5sum: gentoo-flowers-1280.png: No such file or directory
gentoo-flowers-1280.png: FAILED open or read
md5sum: gentoo-flowers-800.png: No such file or directory
gentoo-flowers-800.png: FAILED open or read
md5sum: Jewel-Back-blue.png: No such file or directory
Jewel-Back-blue.png: FAILED open or read
md5sum: Jewel-Back-purple.png: No such file or directory
Jewel-Back-purple.png: FAILED open or read
md5sum: Jewel-Front-blue.png: No such file or directory
Jewel-Front-blue.png: FAILED open or read
md5sum: Jewel-Front-purple.png: No such file or directory
Jewel-Front-purple.png: FAILED open or read
md5sum: LICENSE: No such file or directory
LICENSE: FAILED open or read
md5sum: WARNING: 15504459 lines are improperly formatted
md5sum: WARNING: 33 listed files could not be read
