Hi there and welcome
the Movies are a lot different to how Netflix does this. Netflix streams while with Apple they need to be downloded
For 4-6 MBPS it is right the speeds you say
You can see this here
This is because it first downloads it then it plays it, rather then the way Netflix does it which is to stream the content as it plays.
This you can only change by increasing your bandwidth speed with your provider
If you would like any additional information or assistance, please do not hesitate to let me know.
Else if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated.