The part of the video that she didn’t see - Blue haired guy chuckling and burying his head at her singing, he then looks at her back whilst smiling for a long time with a gaze while she works
Here's a novel excerpt of what everyone saw during the time Dan-I got water:
Eun Jiho smirked, “Did you think we had no idea? Eun Hyung and Woo Jooin… they might have already noticed from earlier. Ban Yeo Ryung is slow at this kind of thing, so she may not know though. If we had no idea, we would’ve bounced off the wall when we saw your gaze at Donnie inside the video that we watched at her house.”
The novel excerpt I just included is a part of another big spoiler. If you want to know about that, then:
During their class trip, Eun Ji Ho drunkenly admits to Yoo Chun Young that he's held feelings for Dan-I for over a year and a half. He confessed to her but she didn't understand he was being truthful and thought he was joking.
Here's another excerpt of him dealing with his unrequited crush:
“If having a crush on her took place suddenly, my feelings should cool down quickly or so, but it doesn’t work like that. I was so annoyed at first but the only thing that comforted me was this. No matter how many times you guys act like that to Donnie, she will never see you all as a guy. This… only this comforted me. I hate myself being such a loser relying on that to console myself, but you guys acting like that is even worse, so I guess I’ve gone through my stormy period of adolescence quite enough.”
From the start where I've been reading this until this recent Chapter, my ML is still Yoo ChunYoung. Like seriously 😭😭😭 I really think they are meant for each other😭😭😭😭 Tho I still like everyone in the gang but I just feel for ChunYoung LIKE DAMN, YOU SO SWEET MAN AND JUST WATCHING YOU BEING INLOVE WITH HER IS TEARING MY HEART! AAAAAHHHHH I just can't uugghhhh. I really hope they end up together
tho I did read some spoilers which speaks otherwise
but still this Heart of Mine will still stick on the 'Yoo ChunYoung x Ham Dan-I' ship no matter how the story unfolds. I will still bless Dan-I's relationship no katter who she ends up with but just know my ship will never be changed hahahha