Check out the doorbell footage, taken earlier this month ... the guy riding a bike with a basket full of goodies gets absolutely NAILED by the employee's ride, sending him straight to the concrete -- and scattering the alleged stolen items all over someone's yard.

The man starts picking some stuff up before she whacks him with the car door -- but he doesn't give up once all seems lost, calling her a "b****" while still trying to recover some of his lost merch. She even chucks his bike away from him as he keeps cussin' her out!

It's a pretty insane clip ... she claims this isn't the first time stuff has been swiped from her store, and he even says he's gonna press charges after he got knocked off his bike -- but she clearly couldn't care less, peeling off as he walks away with his hands full of whatever he could grab.

It's currently unclear if the man was arrested.