context: at Ti8's final, Team LGD played against Team OG. During the draft phase, OG players had some paper, which were statistics of LGD (I guess). Somnus the player said: Ceb is holding a bunch of paper. https://youtu.be/abEDXaPyIOE?t=15. In that final, LGD almost won but they lost at the end. That final is arguably the best final in Dota2 history. The moment when Somuns taunted OG was captured by True Sight, which is a documentary for every TI final. LGD players surely watched the documentary or at least the clip many times.

The first clip you questioned about is from Ti9, a year after Ti8, where OG and LGD played again. Notail the player took a bunch of paper (way too many for drafting analysis purpose) to remind LGD their tragic loss last year. Hence the mind game. Btw, LGD lost again.