Index: lib/plugins/acts_as_watchable/lib/acts_as_watchable.rb
<+>UTF-8
===================================================================
diff --git a/lib/plugins/acts_as_watchable/lib/acts_as_watchable.rb b/lib/plugins/acts_as_watchable/lib/acts_as_watchable.rb
--- a/lib/plugins/acts_as_watchable/lib/acts_as_watchable.rb	(revision 41000:f7b4efce8b3f1efc6927a0355eef9b3ef644bc0b)
+++ b/lib/plugins/acts_as_watchable/lib/acts_as_watchable.rb	(revision 41000+:f7b4efce8b3f+)
@@ -16,8 +16,10 @@
             has_many :watcher_users, :through => :watchers, :source => :user, :validate => false
 
             scope :watched_by, lambda { |user_id|
+              user_ids = user_id.is_a?(User) ? user_id.groups.map(&:id) : []
+              user_ids << user_id.id
               joins(:watchers).
-              where("#{Watcher.table_name}.user_id = ?", user_id)
+              where("#{Watcher.table_name}.user_id IN (?)", user_ids)
             }
           end
           send :include, Redmine::Acts::Watchable::InstanceMethods