From that pic I probably can guess their sexual habit.
Sakaki: Notice that she simply blushing while averting her eyes. Even for a quite type, she seems to be willing to be sexually curious and active. Others think that Sakaki is stoic and cool, so they probably think that she's the one on top or leading her lover. But in reality she's more balanced.
Yomi: Aiyaaa Yomi, you poor girl. Look at how she looks at it angrily with her hand trying to "block" it. That girl is too "stiff" because she needs to act like a mature older sister to Tomo's antiques. She probably thinks that Missionary position is the only position needed in sex. She need someone who can make her feel less constricted and relaxed.
Kaorin: This girl is obviously pretty straightforward and shameless when it's about sex. But she obviously doesn't have a single damn clue about it. Girl need a lot of time to learn.
Kagura: She obviously curious, but unlike Sakaki, she's pretty much still clueless about it. Also those two hands on her cheeks indicated that even with her tomboyish attitude she's pretty much less straightforward than Kaorin. Also note that She's in a swim club so obviously she already saw several men half naked before so we can assume that she's pretty comfortable with men's body.
Tomo: Even with her childish tendencies she obviously understand what she saw. But she looks afraid, maybe she doesn't want to ruin the "Cool Tomo" 'tude she built around her. She will ease up and more understand sex during her college years. But knowing about Tomo I bet the sex will be pretty clumsy.
Osaka: Dude, look at her face, she's fucking ready (pun intended, sorry). If she found the video alone, she will study it to the last minutae. Remember when Yukari got drunk and start lecturing the girls about sex? While the other girls looks surprised or ashamed she simply sit there, writing everything to her mental note, word by word. Most men will think "She looks pretty timid and clueless. I will go slow on her." Only to wake up a couple days later with "HOLY SHIT, WHAT THE FUCK?" face.
And of course she will stand on the door, holding a knife. As usual.