Diana, Pam,
It looks to me like the bird in your video (and in the first two pictures) is an adult female.
I do see some very, very faint streaks that look sort of like "stippling" on the throat, but the bird's plumage overall doesn't look like an immature bird. (Remember that an immature bird would not be molting - that is, losing feathers to natural replacement - at this point, since his or her first body feathers will probably last through the fall, even into winter. Adult birds, however, do a complete body molt when breeding is over.)
When we talk about stippling on the throat, this is more like what we mean:
You can also see the first couple of colored gorget feathers coming in - another sign that this is a young male Ruby-throat.
This is a particularly heavy stippling example, of course, and it can be a lot lighter than this - in fact, some males won't show any at all. But you won't see a female Ruby-throat with this kind of throat pattern unless she's in a very abnormal plumage.
Kevin Morgan
Baton Rouge, LA