Search for [how to hack a wireless network] and look at some of the results. You will see a new feature that shows sub-video results with little play icons. The play icons look similar to the play icons used on Google Music Search.
Here is a picture:
This was first spotted by a searcher at Google Blogoscoped Forums.
As you can see, for the result above, it seems like not all the "related" videos are all that related to my query. In any event, this must be Google's way of getting more video results on the page without taking up all that much real estate.
Forum discussion at Google Blogoscoped Forums.