I love collaborations. That's why I love those end-of-the-year shows and special concerts like SM Town. And this year's SMTown in Tokyo last week had its own share of memorable performances and collaborations, so many of them 
The only disadvantage is that the quality of the fancams varies a lot.
But these are pretty nice ones I could find:
Seulgi & Taemin - Drip Drop
(Seulgi focus, multi cam)
Irene, Seulgi & Hyoyeon - dance collab
Taeyeon & Jaehyun - Starlight
Yunho & Boa - Swing
Those dance performances are so awesome, and I love how happy Taeyeon looks, I live for collabs like these
I'm still watching SMTown Tokyo performances, so I'll be anticipating what other collaborations I'll encounter.
The only disadvantage is that the quality of the fancams varies a lot.
But these are pretty nice ones I could find:
Seulgi & Taemin - Drip Drop
(Seulgi focus, multi cam)
Irene, Seulgi & Hyoyeon - dance collab
Taeyeon & Jaehyun - Starlight
Yunho & Boa - Swing
Those dance performances are so awesome, and I love how happy Taeyeon looks, I live for collabs like these
I'm still watching SMTown Tokyo performances, so I'll be anticipating what other collaborations I'll encounter.