Automatic watchers is a Redmine plugin that automatically adds users that touch an issue as watchers of that issue.
Provides an option to enable/disable the automatic watcher adding feature without having to uninstall the plugin.
A copy of the plugin can be downloaded from GitHub.
Follow the Redmine plugin installation steps at the Redmine Wiki.
Restart your Redmine web servers (e.g. mongrel, thin, mod_rails)
Log in as an Administrator and verify the plugin is enabled at Administration / Plugins / redmine_auto_watchers.
If you need help you can contact the maintainer at github.com/rchady.