I'm with Flying Lawyer on this one - a mistake rather than irresponsible.
There's no evidence that the pilot didn't do a recce, or that the pilot didn't know the wire was there. In fact, given the gentle pick-up and pedal turn away from the wire, it looks like the pilot was fully aware of the wire. What s/he wasn't aware of was the gentle drift backwards which occured before take-off. Without that, the helicopter would have cleared the wire.
I do a lot of work with pilots conducting serious low flying ops, including required flying sequences under wires. We know from experience that when pilots hit wires they are usually fully aware of the wire's presence.
There are well-known techniques to reduce the risk, but the reality is that being aware of a wire doesn't stop pilots hitting it. If you could solve that problem you deserve a Nobel prize.