Hi Drew, 

I have just watched the video and the girl in it is a typical young woman from the Paris region.

I personally think the lilt is thought attractive and it has become a must for YouTubers, young hopefuls who try to make a lucrative career out of it.

I wasn't aware of it in France but in England, it has become fashionable to use an upward inflection to imitate other countries like Australia.

Take a look at the following BBC article talking about that very subject -

https://www.bbc.co.uk/news/magazine-28708526

Hope this helps!