Youtube is full of high school and uni presentations so maybe it's not been the experience of some posters but it's not necessarily unusual. I think her presentation style is fine. It's a little exaggerated but honestly, that's what comes off as engaging and good style for some profs and we all know that when were nervous and presenting, not all of us behave totally "naturally". To speculate over a competitive relationship between her and the over girl...female friendships are complicated and to me you can really love, support, and respect someone but also have a natural edge of competition. I think it's natural to feel that way at times and being an adult is not letting those thoughts translate into actions or words that deliberately hurt, sabotage, or otherwise make the relationship toxic or awkward. I don't see anything like that, just slightly different presentation styles.
Usually I roll my eyes when someone brings up supposed weight loss. But as a skeptic, wow she definitely has lost a lot of weight and for that to visually translate it's not just the 5 or so pounds of water fluctuation or whatever. Sometimes people lose a bit of "baby fat" with a bit more cardio in their early 20s but seems to have lost quite a bit all over and I find that this change is more often in girls who are taller unlike Ruby. I do hope she is doing ok as the pressure to look a certain way is probably exacerbated by her social media presence. Smart girls aren't supposed to care too much about glamour but there's also the stereotype of the academic who is so caught up in studying and scholarship that she forgets to eat and yet looks lithe and pretty without seeming to try to hard.