At 4 GB your flash drive was already formated at FAT32 and should have worked in your iMac and TV. Based on the specs for the TV and the capabilities of your iMac utilities the MS DOS format is the only option available to you. Try it a 2nd time and see if that helps. Now if you could find another machine running Windows; a friend’s, a family member’s, a library’s, etc you could try formating the flash drive as NTFS to see if that solves the problem.
Are you sure the file format of your video is supported by the TV? Some TVs only read AVI files. Maybe that’s the problem.
