This cap will not solve any problems they have with the capacity of their network. The pipes will be clogged when all those people are watching movies and it does not matter if it's 4.7GB or 20GB. If they cannot provide enough bandwidth at certain times at day it does not matter if people are downloading 10 GB file or 1.5GB file at that moment they are still clogging your pipes. Nobody will change their Internet usage times because of the cap so the congestion will remain.
This cap will not solve any problems they have with the capacity of their network. The pipes will be clogged when all those people are watching movies and it does not matter if it's 4.7GB or 20GB. If they cannot provide enough bandwidth at certain times at day it does not matter if people are downloading 10 GB file or 1.5GB file at that moment they are still clogging your pipes. Nobody will change their Internet usage times because of the cap so the congestion will remain.