When you're conducting an interview, obviously you're not going to be able to remember everything the subject talks about.
That's not the point.
You should look like you're listening, though not necessarily listening.
More like prodding, mirroring, energizing, and guiding the conversation.
But the actual detailed recalling of the information, the listening, happens in the editing room.
So don't worry about feeling overwhelmed about everything the subject says.
You're not expected to know, understand, or respond to everything they say.
That's not the point of conducting a documentary interview, anyway.
The point of a documentary interview is to keep people talking.
And to capture the best version of that.
To quote Errol Morris: