Ylvis recorded the music video for the song that was the top trending video on YouTube for which year?
Ylvis:  Their song and music video "The Fox (What Does the Fox Say?) The Fox (What Does the Fox Say?):  The top trending video of 2013 on YouTube, "The Fox" was posted on the video-sharing website on 3 September 2013, and has received over 690 million views as of August 2017.
2013