While non-pharmaceutical interventions (NPIs) such as stay-at-home, shelter-in-place, and school closures are considered the most effective ways to limit the spread of infectious diseases, their use is generally controversial given the political, ethical, and socioeconomic issues they raise. Part of the challenge is the non-obvious link between the level of compliance with such measures and their effectiveness. In this paper, we argue that users' demand on networked services can act as a proxy for the social distancing behavior of communities, offering a new approach to evaluate these measures' effectiveness. We leverage the vantage point of one of the largest worldwide CDNs together with publicly available datasets of mobile users' behavior, to examine the relationship between changes in user demand on the CDN and different interventions including stay-at-home/shelter-in-place, mask mandates, and school closures. As networked systems become integral parts of our everyday lives, they can act as witnesses of our individual and collective actions. Our study illustrates the potential value of this new role.