Sighthound Video requires you to be logged in for the application to run. To ensure that others do not have access to the video data on the computer, there are two options:
On machines that have Fast User Switching enabled, you can have one account that is dedicated to video processing. Leave that account logged in (with a password) and switch to other accounts using Fast User Switching.
On machines that do not have Fast User Switching enabled, like Windows Server or Windows machines that are on a domain, you can lock the account when unattended. On Windows, this is done by hitting the Windows key + L or selecting Lock from the Start menu.
If you know your computer will shut down periodically, you can set up Sighthound Video to resume when the computer reboots. For details, see Running Sighthound Video automatically when you start your computer.