If the same stored chunk of a movie file is encrypted the same and is the same string of data in transit, then it’s possible to know who is downloading all files, as long as you have the file. I believe this is one of the core principles of the network.
Wouldn’t it be extremely easy for your ISP to record your encrypted traffic and know you’re downloading X file from their big list of encrypted movie files?
Only if your ISP could decrypt the crust packet which uses authenticated_encryption. So you are OK there 
The best they can determine is that you passed it on. And only 2 countries have ever gone after a Tor exit node (passing on a file).
And the packets of a chunk are each encrypted between nodes.
So no the ISP cannot, all they see is encrypted packets. They cannot decrypt them to get the chunk being passed.
EDIT: beaten again