Where is Google Voice and Video installed?
You've already looked in the standard spots for application installs (Applications folder, Utilities folder,etc...).

However, if you've installed Google Voice and Video (aka Hangouts), you won't find an application to run (on OS X or Windows). This is a plugin for your web browser - not a standalone application. 

Read here for details - but in short, you should run the installer (you've likely already done this), then quit and restart your web browser (Safari, Firefox, or Chrome - whichever you use). The features of Google Voice and Video will then be functional, and you can then use video chat with other Google Video users.