Yes, doesn't look very clever.
Don't put too much faith in voltage detectors or even multimeters. Ghost and induced voltages can easily be picked up.
As yours is non-UK practice, it's hard to say, but threat it as live until you know better.
Most UK mains wiring is "Twin and Earth" or T&E.
It has a distint oval profile. Just looking at the images doesn't tell you much, but is there a groove running down the centre of the outer sheath or is it a trick of the light?
There is a cable called figure of eight and is mainly used for low voltage circuits like doorbells. I have seen much thicker versions used in audio systems, especially in high power speaker connections.
To be honest, it's hard to say.
Another case of undocumented cable or lack of cable identification.