If none of your videos exceed 4GB in file size, you should be using FAT32 as this is the most compatible filesystem and works on all Smart TVs. However, if any of your video files are over 4 GB, you will need to use either exFAT or NTFS. Determining which of those two options will depend on the device it will be viewed on. Both Windows and Mac can read from NTFS and exFAT. However, Smart TVs will often support one or the other.
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Sony TV's typically support FAT32 and exFAT, while Samsung and other brands typically support FAT32 and NTFS. Some TV's may even support all three file systems.