It can be done with a simple command. Once Totem is running, open up the terminal and enter the following line:

$ sleep n && totem --quit

Where n is the number of seconds you want to have elapsed before Totem is closed.

Explanation of the command

This is a very simple command, and if you want to learn more about using the terminal you should consider reading a bash tutorial, like this one.

The sleep n command waits until n seconds have elapsed and then the next command can be run.

Writing && after it tells the terminal to run another command as soon as the previous is finished, which is why I have written totem --quit after it.

You can do many more actions and not just quitting. Many applications in linux have a command line interface, which allow you to do this. To see what actions you can do on them through their interface, it is a good idea to check its manual, by running in a terminal $ man <application>; or help text, which is usually shown by running in a terminal $ <application> --help.