She hadn’t stopped a threat. She had unlocked one.
Modern browsers (Chrome, Edge, Firefox) have for NPAPI plugins (like Flash, Silverlight, custom video plugins). However, many older NVRs (2015–2020) were designed for Internet Explorer or legacy Chrome and require a local plugin for: webplugin nvr 147 download verified
If you cannot get the plugin to work or want a safer approach: She hadn’t stopped a threat