We understand your need for this feature. However, we are afraid that there are a few limitations that are preventing us from taking this up for development. We will not be able to exert control over the file size for download and the native file window. Also, because of security concerns we will be unable to take this up for implementation right away. However, we might add this to our development roadmap in the future and we'll be sure to post updates in this space once we do.