I think I was looking for that functionality in past and came to same conclusion - it is not possible. At the end I did not need it, but just a quick solution for you could be…
If you implement additional class to keep list of files in the database as it is described in afterSaveFile trigger AND you are sure that everyone that wants to download the file will first look for the file through that additional class, then you could use find trigger to somehow assume that the user is going for that file.