The government wants to offer data from a computer or some other mechanical or recording device.
Can a NCIS agent testify about the contents. No. That violates the best evidence rule, Mil. R. Evid. 1001.
Courtesy of federalevidence.com here is a link for a recent case dealing with GPS information:
Ninth Circuit reverses an importation conviction based on the admission of testimony about GPS data which violated the best evidence rule; case demonstrated the application of the best evidence rule under FRE 1002, in United States v. Bennett, 363 F.3d 947 (9th Cir. 2004)
The Best Evidence Rule under FRE 1002, which can be misapplied, requires “the original writing, recording, or photograph” to be introduced when offered to “prove the content of a writing, recording, or photograph,” unless some other exception governs. A Ninth Circuit case demonstrated application of this rule to global positioning system ("GPS") information.