That should be doable in a plugin. The points could be kept as a custom field with the topics, posts and/or users.
Some questions to get the functionality straight:
Are those points solely based on the length of the response?
How is “enough” determined?
I assume “the file” is the story? Do they need to take explicit action? I.e. is there a button “stop people from downloading the file” which is unlocked by “enough responses” ?
How is the number (of points?) a story receives determined?