As matija points out, getting along with the system administrtator is good for your health.

If you have no choicee but to download the file, consider rsync. rsync is good at fetching only the changed portions of files. It should be suitable for minimizing the portion of the file which needs to be fetched each minute. However, you might need to provide some pre-processing to detect rollover, as I'm not sure how rsync would handle that.