I searched for Quickflix it appears to be an Australian DVD + streaming service similar to Netflix. I don't think it downloads the video to you're TiVo you put it into a queue to be watched while "Streaming". Look at the bottom of "My Shows" or "Find TV, Movies, & Videos" for the Quickflix app and play it from there.
If you are in Australia look at this post in the TiVo NZ/Australia
section of the TiVo Community.