Adventure Time - The Music Hole video

I too am curious about this.

I feel like it's both; it looks like a distorted version(a reflection over the cracked sphere that used to serve as Finn Sword's place) of the first time Finn Sword shook his head, so it could symbolize the guilt Finn feels which leads him to the Hole's song. This guilt is reflected upon through the song and leads Finn to find solace as Finn Sword's memory is carried out, kinda like a dance comparatively.

I think that he is dancing to the music because his face is more of a solemn face - Finnsword would wear a different face if he would be saying no.

The hole says "those with a deep sense of loss in their hearts", not those who have experienced great loss. While Marceline and plenty of other characters have gone through stuff, none of them are currently being emotionally consumed by feelings of loss. Marceline lost her past with Simon, but accepts this as she behaves more friendly towards Ice King when she realizes he doesn't remember anything; she has no reason to hang on and uses it as an opportunity to make something new. She also lost her humanity and mortality, but accepts this when she realizes it is necessary to contain the vampire essence. Finn is a hero who devotes his life and being to protecting others, and directly and physically kills a helpless innocent because of his carelessness. Not to mention a helpless innocent he can empathize with more than any other being; himself. He then does the same thing he did after being deserted and having his arm ripped off by his dad; closes himself off and becomes consumed by his own unhealthy emotions and thoughts. The point is Finn just recently went through something and as a character tends to dwell on things, so he has a deep sense of loss in his heart that is evident through how he kind of halfheartedly acts out his role as a band judge, which he would be normally really excited about(seeing all his friends and etc.) Sry if the rantyness of this text made it seem like I was trying to shove in your face "your viewpoint and thoughts are incorrect" in typical internet-user fashion, I'm just trying to share my viewpoint, and to my knowledge I'm not capable of writing under 250% of the required information(without any comprehendible sentence structure) in doing so. Thank you for reading all of this and have a nice day ♥.