Group course searches by video, sort videos by number of mentions

Suggestion from EC: "I think grouping search results by video is a good idea. One thing I wonder is could you group them by video, and then order the results by videos were the searched phrase occurred the most to least frequently? (I assume that in most cases mentions are kind of separated into discussion of topic or passing mention and that the passing mentions are probably less likely to be the search results students want — this may be a completely incorrect assumption…)"

I imagine an interface that presents 2 results from each video, but that can be expanded (or subsequently collapsed.
```txt
> Video8 Name (6)
2:31 *grep* is a useful tool
2:39 the options of grep are
See more[fewer]
> Video 3 name (1)
1:23 let me just *grep* that
> Video 9 name (1)
```