Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 280)

Movie Files Exceeding 4 GB
Even if you record a movie exceeding 4 GB, you can keep recording without interruption.
Caution
When importing movie files exceeding 4 GB to a computer, use either EOS Utility
or a card reader (
). It may not be possible to save movie files exceeding 4 GB if
you attempt this using standard features of the computer's operating system.
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