1080p 60i video camera?

1080i60 is one of the standard ATSC broadcast formats so it there's some justification to support it.   And it requires less data throughput than 720p60 (which is the other ATSC standard format).

I'm not familiar enough with the Nikon to know if it's 1080i60 mode is really interlaced (i.e., it reads 60 frames from the sensor every second and records the even and odd lines from successive images in separate fields) or if it's simulated (i.e., it reads 30 frames from the sensor every second and records even and odd lines from the same image in separate fields).   Some cameras list "1080i60" in their specs even though they're really doing the latter and encoding the output into a pseudo-interlaced container file that complies with the standard.