Apple TV/FM Radio System - Manual (Page 38)

3 Before you attach the TV cable, make sure it has an F-type
coaxial cable connector.
Important Do not attach or detach the coaxial cable while
the computer is turned on.
Note: If you want to view closed captions on a videotape
that has them, you must connect the VCR to the TV/FM
tuner card, not the video input card. For instructions on how
to do this, see the Appendix, “Viewing Closed Captions on
Videotape.”
F-type coaxial cable connectors
31 Installing the Card and Software