mbop aims to use the least cookies possible. They are:
This is used to make sure you stay logged in between page loads. Without this, you would have to log in every time you navigated around the site.
This is used to validate that it is you submitting a form, not a malicous actor impersonating you. For more information, check out cross-site request forgery
Additionally, the service vimeo is used to display videos, which has it's own cookie policy