My copy of that photo, as well as some other photos where the girls wear outfits of this style, was dated 1908 when I saved it, but I'm not sure about that. There are 1908 photos where they seem to look noticeably more mature, and this is closer in appearance to that film footage. My own guess for the footage has been 1906 since I think Alexei looks a little younger than in some of his long-haired photos and there's a 1905 Polar Star photo where the girls are in similar outfits while he's still being carried by a sailor. But then there's that ship photo of the whole family that I've seen dated 1907... I too find these early holidays tough to date.