Google started to show the most relevant web page at the top of the video search results. The strange OneBox result is only displayed for navigational queries, which usually return a single significant result.
To try this feature, go to Google's homepage, enter a random query, then click "Videos" in the sidebar and enter a navigational query (for example: microsoft).
Sometimes the ads and the top result take so much space that they push video results below the fold.
42 minutes ago