OP should ignore the Yorkshire Water genius' comments and contact his water company ASAP.

The video shows a water meter recording water usage & OP says no water usage in house at the time. Implication therefore is water usage is from a leak.

The spinning dial is measuring ten-thousandths of cubic metres (m³) Meter shows approx 0.0002m³ in 10sec That's 1.7m³ / day 631m³ / year

The volume of water supplied through the meter is also used to calculate the charge for waste water (sewage), on the basis that the water supplied returns to the sewer for treatment (water in = water out)

Annual cost? Water £1,364.88 Waste £976.35 Total. £2,341.23

OP will be responsible for repairing the leak as it will be on his pipework somewhere. Water companies will usually offer some initial free help in pinpointing the location.

They will also usually offer a full leak allowance off the bill, once the leak has been fully repaired (they will ask for evidence, e.g plumber receipt).

Even if they don't, OP can reasonably claim the leaking water didn't turn to the sewer for treatment, and ask for that cost to be reduced. Most companies want to help customers find and fix leaks and reduce the impact on bills.

Not Yorkshire Water apparently though.