I've just wasted time looking for close-ups of the connections. I found a fascinating thread with pictures where someone was modding the Videosphere "into a working computer" with a colour display - but it tails off before finished. Don't look at this unless you're curious and don't mind a cul-de-sac
Computersphere - moding a JVC Videosphere into a computer 20 December - bit-tech.net Forums
These are the most complete specs of the Videosphere that I can find:
Black and white television receiver mounted on a platform. The videosphere has a spherical orange plastic casing with the tube, electronics and product name badge contained within. Controls for channel tuning, contrast, brightness, vertical and horizontal hold and volume are mounted at the top of the unit in a small recess. There is also a chain that the unit can be hung from, an antenna and entry for an earplug. The power cord comes out of the back of the unit. The whole sphere sits in an orange cradle mounting that is a squat square shape and the sphere can be secured to this or released from it.
So I guess that the sole input on the unit is the aerial? I wonder if yours was made before video recorders got going, you wouldn't think the Japanese would have missed out on a connection.
I hope someone comes along with expertise
clemenzina