Screenshots and Waterfalls are features of a Transaction monitor. They are described in the KB articles Working with Transaction Screenshots and Working with Transaction Waterfalls.
These features were enabled for Enterprise subscriptions only. Now they are available for Business subscribers as well.
As a Business subscriber, you now can enable the Screenshot and Waterfall options for each transaction step. In addition the Screenshot is available in your list of actions to add to transaction steps. When you add a Screenshot action, you determine yourself where in the sequence you want to take the screenshot. Keep in mind, that each waterfall and transaction counts towards the transaction monitor credit calculation. The details for the calculation are described in Transaction monitor credit calculations.
In the KB article Using transaction screenshots and waterfalls you find detailed info on how to set up and make the most out of these features.