Question about subscriptions

Hi,
I have a question about the operation of the subscription mechanism.
I have subscribed to a Youtube channel that hosts a number of large (500-800MB) videos. Of course, this “quickly” fills up my NAS storage space, so I’m thinking about moving some of the files offline. But how would that interact with the way 4kDownloader determines which videos it has already downloaded in the subscribed channel and which videos need to be downloaded? IOW, won’t it download again the videos I will have taken offline?
Thanks in advance for clarifying this.

Best regards,

Stéphane BARIZIEN

P.S. I asked that question by email on Fri 2018-03-23 06:47, never got an answer...