The presumed owner of said fence is a gal who's just overwhelmed by the cuteness of it all, which adds an extra layer of entertainment to the proceedings. Three of the four cubs eventually clear the fence, hot on mom's trail. The fourth scampers off screen near the end, having given up with the climbing and presumably opting to work smarter, not harder, and maybe just go around the end of the fence.
Just some simple summer fun. And, hey, props to video operator for just enjoying the show and not making the foolish (but still often-made) mistake of doing something that might have upset the sow and started real trouble.