Now that we have the persistence and retrieval of video thumbnails figured out, we need to actually display them in the native app.
In this diff we just retrieve the thumbnailURI instead of uri from mediaInfo for media of type video.
This enables a minimally viable end-to-end video experience.
NOTE: Still need to take a closer look at the reportURIDisplayed(...) logic and understand what's going on there better before landing this diff.