If you delete the 'it' clips the cards will play only one clip and then skip to another card, because the transitions are missing.
Which seems to be true but wasn't something I had ever noticed before. I took the 'it' clips from
f0606 and Jia will dance one, two or sometimes three clips but even with 'play all clips' selected, the app jumps to another card after two or three clips without the 'it's' in between.
I've never even thought of deleting 'it' or demo clips, I just go get a bigger HDD and keep going.