Right click again on the new group tile to edit the tile. Here you can change the name, color, and image of the group tile.
If you have a group full of embedded tiles like this one, you can right click on the group and press autoplay. This automatically opens the videos within Symbaloo and plays them. You can see all of your embedded tiles by clicking the arrows on the side, or you can press the four squares button in the top left corner of the window to show you all of the embedded tiles at once.