The present chapter analyses how far right activists, digital media platforms and audience interplay in the production and diffusion of anti-immigration activism through an Actor Network Theory approach (ANT). It considers societal vigilantism as a technical mediation and, following the ANT central notion of translation, examines the co-influence between humans and technical artefacts. We focus on one case study of a YouTube livestream of an influential figure of anti-immigration societal vigilantism, Lauren Southern, in what was referred to as the French Alps mission, in April 2018. That mission brought together anti-immigration activists, under the banner of Génération Identitaire, who organised a blockade to prevent migrants from crossing the border between Italy and France. Based on a microanalysis digital ethnography of a livestream video posted on her YouTube channel, on which Southern is live-documenting both her actions and those of her co-militants, as well as giving her perspective on the role of digital media and the actions she is involved with, we come to two main results. First, we show that YouTube supplies symbolic and emotional content to individuals who reject mainstream media for all sorts of reasons, but which criterion of assessment rests on emotion, beliefs and wishes rather than on a thorough fact-checking process (as traditionally executed by mainstream media). Secondly, our chapter contributes to the current debates about post-truth. It demonstrates how truth is not only resting on emotions and beliefs – rather than facts – but also on infrastructure that blends as series of human actions, such as sharing, clicking, and commenting, with non-human actants like algorithms and collaborative filtering, whose materiality and performativity affects the economy of information. The assemblage altogether contributes to turning “fake news” and harmful discourse into political canons whose availability is augmenting, thus bringing the risk of matching a growing number of “interpretative communities”.