Roku BIF files
I just did a little code cleanup and released one of our internal tools under the MIT license.
For on-demand video, Roku devices use a custom file format that stores a number of images (video frames) in a single file. This file is used for trick-play where you can see a preview of what the video looks like when you fastforward and rewind.
The format is a very simple archive format with an index and a number of JPGs embedded. We re-use the Roku BIF files with a custom clappr player plugin (we will likely release this as well) along with a mouseover effect on our video lists page.