Message received via email and posted here for others to learn the answer:

Q: What does this product monitor? HTTP? FTP?
A: The product monitors the directories, files and user accounts of your Joomla! website install on the hosting server. The website will be HTTP or HTTPS, but if there are directories or files that are used for FTP (or any other) services, these can be included, as long as they are placed inside the root dir of the website.
For user accounts, the user table in the website’s SQL database is monitored.

Q: Is there the ability to monitor multiple sites from one install?
A: No. The install will only monitor the directories/files/accounts of the website where it has been installed. In other words: you will need a separate install for each website to be monitored.
The Business license does not limit the number of websites where you may install the plug-in, as long as the websites are owned by you or your employer.

Q: Can I set the polling/monitoring interval?
A: Yes you can. This is an option included in the Business and Standard editions, not in the Trial edition.
The plug-in is only fired upon a website call (either back- or front-end). For back-end calls, the plug-in is fired upon every page call, for front-end calls you can set the interval, ranging from maximum ‘once per minute’ to maximum ‘once per 24 hours’. Setting an interval reduces the server load.

Q: Is there reporting?
A: Yes there is. The notifications through system warning messages contain little detail, in order to keep sensitive information away from potential hackers. You can however configure notification by email. These email notifications include the details of the events that have been detected.