Welcome to CH.
My remarks are more of an opinion, but not a sure solution.
1,) There needs to be a consensus about the issue. How important is movie download to your people? Can the download be done at night?
2.) What is the speed of your local internet provider? Can you upgrade to a higher speed? Movie downloads can be very long if the file is in the DVD format. Other formats, AVI for example, are much smaller. Would limiting downloads to just ACI be helpful.
3.) I would not recommend a "Bandwidth Manager" device unless you company really needs high performance and fair use of available bandwidth. These devices are expensive and require more management.
Here is a general definition of the term and some links to other sources,
http://en.wikipedia.org/wiki/Bandwidth_management.
Again, my opinion is to resolve the issue with Office Politics rather than more equipment. But maybe somebody else has a sure fix for your question.