The tabs across the top of the Timeline pane show all the Group Tabs that exist in the current Matinee sequence. Group Tabs are a handy way of organizing groups and tracks based on their function. Their use is completely optional. For very simple sequences, you could simply leave all groups and tracks in the default All tab. But with complex sequences, like those used to create in-game cinematics, you will do best to make use of these tabs as the number of groups and tracks in the sequence can quickly add up and become unwieldy to navigate. The All tab will always show all the groups and tracks in the sequence so adding related tracks to a corresponding group tab can be a quick and easy way to find and edit those groups and tracks. You can create your own custom tabs in addition to those provided by default to further organize your groups and tracks based on any criteria you choose.