Vivaty Player
The Vivaty Player is a ~4 MB brower plug-in. You will only have to get the Vivaty Player once, and it should take about a minute to install over a high-speed connection. You will automatically be prompted to get the Vivaty Player as you access Vivaty. Vivaty does NOT install anything other than the player necessary to access the 3D content.
If you use Firefox...
1. You'll see a page that looks like this, and a pop-up will ask you whether to save the Vivaty Player to your computer.

2. After you save it, click on the player to install it. You might see an icon that looks like the shot below:

3. The player will install and then you'll see this page when it's finished, without a popup. Click the LAUNCH VIVATY button and you'll be redirected into the Vivaty experience.

If you need to download Vivaty Player again:
Try this link: http://www.vivaty.com/downloads/player/