I had this video saved on youtube but seems it now private or deleted. I tried using Wayback Machine and got not results (so can't confirm if the link is correct.) I tried too looking in twitter @nocontextcookie and videos on niconico.
Thing was about Nazrin walking by singing and kinda dancing while playing an instrument, other characters of touhou were joining her on the travel, one of them had a tambourine I think. Always walking btw and song was pretty chilling.
Video of reference. That kind of art style were the characters of the video I'm looking.
https://youtu.be/FDQ8veAk2L8

Also on this one there are insturment that showed up.
https://youtu.be/NWQFn79p2cc

Btw, the length of the video I don't remember accurately but it was longer than 3 min.