Yes, I think it was used on cameras pre 2010, like HDV camcorders and point and shoots before the wide (but short) release of 3D camcorders and the Fuji W3/Pan 3D1 still cameras. It requires the USB port right? They've been removed now without any similar control port. There's a cable trigger for mirror-bodied cameras that will do sync like with a pair of Canon 5D's, will work for video too.
The only other way I know of (without genlock), and I'm curious to test it out would be with a pair of GH4's and use a single external recorder (video only, I believe). I believe this would be true sync genlock, only problem is the interaxial with a side by side rig would be fairly wide about 5 inches at the closest, maybe more with HDMI port used, have to go with a mirror rig.
The other one I'm interested in still is a pair of BM micro cinema 4K cameras. They have HD SDI outs that could run to single external recorder for genlock. One camera can be inverted (I believe) with the top 1/4 20 mounting hole (I think they have a global sensor so shouldn't have rolling shutter artifacts upside down to deal with which is bad for 3D). I haven't seen one in person to confirm the mounting holes line up top/bottom but if they do you could then have the right camera upside down and have the left SDI out on the left camera and the right SDI out on the right camera as it would be upside down for closest interaxial. The closest interaxial would be 3.25". Only problem is the cost which is 1300 each plus an external recorder and media. Would be close to 5k all in. Wish the cameras were a little cheaper. You can pick up a used GH4 for less.
Not too many solutions for 3D now, have to use duel cameras but lack of genlock in prosumer and consumer cameras is a problem. Genlock ports, usually larger more expensive cameras. GoPro maybe if they add the cable sync, I guess they added one for VR awhile back, maybe that works. There was the Lytro cameras with lightfield sensors but that's gone now and they were only stills. Company finally figured out people didn't want low resolution adjustable focus images. With further development I think this would be interesting for 3D but really just for macro where dual lenses are next to impossible. Or in cinema where they're using single lenses anyway (almost all converted movies now anyway). There's Ratrix
cameras, I think the same concept, and even shoot video, but no prices listed so you can guess you can't afford it.