I notice you're asking about downloading and installing Keylight 1.2 (often referred to as version 1.2 or similar, not "12") for After Effects CS5.
He navigated to the Effects menu, and there it was: Keylight 1.2. He felt a surge of excitement. He imported his green screen footage and applied the effect. after effects cs5 plugin keylight 12 download install
Since After Effects CS5 is 12+ years old and cannot run on modern macOS (Catalina and later) or fully support Windows 10/11, consider these options: I notice you're asking about downloading and installing
If you have the installer files, the plugin is usually located in an "Extras" or "Payloads" folder. Copy the Keylight folder into the following directory: after effects cs5 plugin keylight 12 download install