Riot police and 'Kill the bill' protesters clash in Bristol

The video describes a situation where police are pushing back a line of protesters. Despite six hours into the process, there are still 500 to 750 protesters. Riot police are advancing the line away from a police station, facing resistance from protesters who refuse to move. The police line has moved forward by 20 to 30 feet in the last 10 minutes. Clashes occur as protesters resist, and police make concerted efforts to move them further away.

Describe the resistance faced by the police from the protesters.

What is the significance of the police line moving forward?