I refused to give in. I formatted the flash drive in my iMac again. I then dragged the two files I downloaded Brinno>Support>Setup TLC onto the flash drive. Installed fresh AA batteries and the flash drive. I turned on the TLC 100 and let it run facing my breakfast room table. After a few hours I removed the flash drive and connected it to my iMac. There in the drive was an .avi file. I double clicked the file and Quicktime opened. There on my iMac was a recording made by the TLC 100. I am back in business.