.mod files are a problem. Are you shooting in 4:3 or 16:9 mode?
What app are you using to convert them ... and what are you converting them to?
The .moi files are index information associated with the .mod files that contain the actual video.
MPEG Streamclip should be able to convert the .mod files. You may need the
QuickTime MPEG2 Playback Componen, if you don't already have it on your Mac. ($20 download from the Apple Store). (You may need to change the .mod file extension to .mpg then open it in MPEG Streamclip.) If you are shooting 4:3 then in MPEG Streamclip convert the videos to QuickTime using Apple DV/DVCPRO-NTSC compression (this is a selection on the conversion screen).