Couldn’t you just subscribe for a month, download the videos and cancel the subscription? Just slap a new 2 TB hard disk on your computer and start downloading 24/7 until the disk is full. Surely that’s enough stuff to watch for several months.
The normal use case for these apps is you download, then you only have access while you're paying for the service. If you put your plane in airplane mode for Netflix, I believe you have a few days to reconnect or you won't have access to your downloads.