...Two things came to mind:
suppose UF isn't paying for these lessons for Sayashi? I remember Abe and Goto (MM) went to US for lessons like this. Probably did it for Abe as it was like for a few days and was a part of TV program (Asayan or some other oldie show) they did way back. Goto was in LA or something for a bit longer, maybe half year? Don't remember all these details nor particular care to look up, just remember bits and pieces. It could very well be paid by Sayashi household or her income earned + salary for being still under UF, but I wouldn't necessarily rule out UF footing the bill as well. Not as charity, but as contract agreement/investment for her to continue her activities under UF after coming back, etc.
It's a case of being curious in potential business side rather than private stuff - I don't really care on all these other stuff, even if I happen to live in the same city.
Upon a quick glance, it just reminds me of similar private group dance practice footage I saw from ex-C-ute Murakami Megumi 2-3 years ago - although in her case, she posted them herself on her twitter account. Not really seeing that much difference - then again I don't know much about dancing to know even if there is.