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.

From this article on uninstalling Hangouts, we can deduce the install location is

/Library/Application Support/Google/GoogleVoiceAndVideoUninstaller.app

You can uninstall it (which is why I found this article) by running

/Library/Application Support/Google/GoogleVoiceAndVideoUninstaller.app/Contents/MacOS/GoogleVoiceAndVideoUninstaller

If the program is on your hard disk you can search for it with the loupe/glasses symbol in the top right of the screen. Click on it and type the name of the program. It will start to populate a list below with suggestions. If you spelled the program correct it will appear in the category Programm. Just hit enter and you should be fine.

Note that this is only one of many possibilities to start a program. But in mine opinion the best if you do not know where the program is on your hard drive.