Unfortunately, this script appears to no longer work reliably. Currently it formats the page curiously (putting the group watch icon in various wrong places all over the page and header) and clicking to show the list of photos doesn't populate w/ images from groups. I was able to get it to partially work by combining it with another script which allows you to tag groups. After using THAT script too, you can see thumbnail previews only for groups you've created a tag for. Out of the box though, this doesn't work and needs to be updated.