I think what the video creator is saying is to create secondary databases that store ancillary data about your main bases then you can reuse that data for other automations or process. There are a ton of uses for this method, I have been doing this for years, just didn’t call it Operational Databases.
For example, your main base has a list of employees and their Role at the company. This list was created 5 years ago. When Jon started 5 years ago he was a Junior Sales Rep, then 2 years later he changed to a Sales Rep, then a year later he was a Senior Sales Rep. Look at the table today we only see that he is a Senior Sales Rep. Now if you had an Operational base that stored each of those changes, we can see what Role Jon was 3 years ago. Maybe we want to email all employee that have been Jr Sales Rep in the past 4 years, you wouldn’t be able to do that in your main base as Jon is currently as Sr Sales Rep.