Masked thugs were filmed on dashcam hurling rocks at a car carrying people looking for evidence of illegal hunting.
Hunt saboteurs believe police forces around the UK are turning a blind eye to those ignoring the 2004 Hunting Act.
The footage shows three men riding a quad bike towards a van being driven by West Yorkshire Hunt Saboteurs. Two rocks smashed the windscreen before the balaclava-clad men fled the scene in North Yorkshire.
The hunting lobby appears to be becoming increasing violent in its attempt to continue the bloodsport unchecked.
Footage emerged at the weekend of a woman rider aiming her horse at hunt saboteurs before striking a man repeatedly with her crop in East Sussex.
Last week a female monitor was assaulted by a hunt supporter in Warwickshire.
And in the West Midlands last month, a farmer was filmed using his quad bike to attack hunt saboteurs.
In the last two cases, the assaults took place as the hunt saboteurs were leaving without offering any resistance.