I am not sure about this sentence, specifically how to interpret the part where it says "marking".
I'll give you some context first. The speaker is a musical actor and he is rehearsing a choreography; in the same room, there is a former teacher visiting the school where he used to teach. The actor is talking about this man.
"The only pressure I feel, honestly, is Mr. Smith in the room. And he has that command on the other side of the room when you, like, you know, you're just kind of MARKING it/that [not sure from the audio about the "it/that'] a little bit and then all of a sudden, you look over and you see him and you're like, 'Okay. Let me dig a little deep.' ".
Please, can someone explain the meaning of that sentence?