Indirect pathway of movement and Parkinson's?
The dopaminergic neurons of the substantia nigra pars compacta are a part of neither the direct nor the indirect pathway. The dopaminergic system rather acts as a modulator between those two pathways. More dopamine steers the system towards the direct pathway, less dopamine towards the indirect pathway.

One of the best explanations of the basal ganglia that I've ever seen were video lectures by Dr. Najeeb on youtube.

explanation of the basal ganglia pathways

pathologies involving the basal ganglia

At the beginning of the second video there is a short review of the pathways he explains in the first one. At 5:06 he starts talking about Parkinson's disease.

A paper about the topic:

Functional organization of the basal ganglia: Therapeutic implications for Parkinson's disease (Obeso et al. (2008)