It's based on who has the most and highest ratings in a given contest.
For example: a creative could have 20 likes in a given contest, but if another creative has even one love they'll take the first trending spot. However, if the creative that submitted 20 likes ends up getting a love then they would take the lead, because while they both have a love, one of them also has several likes.
The 2nd and 3rd spot work just like the 1st spot except they have the 2nd and 3rd most and highest ratings.
I'm assuming the confusion may have come from Grant trying to explain if there are no loves the creative with the most likes will take the first spot, and if there are no loves or likes then the creative with the most on the right track ratings will get the first spot.
Hope that helps 🙂