I've just watched a few parts of the video and I'm pretty sure it's my language lol.
It's kinda difficult to hear, but the guy that came says something like "Ty ji máš nějakou úzkou ne?" meaning something like "You've got her (pussy) pretty tight, don't you think? / You have a pretty tight pussy, don't you think?" (he doesn't say the word pussy, but implies it)
Followed by her saying "want more?" and then "or not?". Then they proceed by exchanging a few words about her tight pussy lol and the other thin girls saying "you know how to make a guy cum girlll".
Hope that clears any confusion :D