I watched the video (though only this video, not the rest of the series, because I only have so much time) and left a comment on it with several elements that are wrong/questionable, so if that's alright I'll edit it slightly for here.

-Thursday is not Thor's holy day. The reason why it's called thursday is because, in Latin, the names of the week were connected with gods and Thursday was named after Jupiter. As they were both deities related to thunder, the Germanic peoples who conquered the Romans translated it to their own gods and then the custom spread eastwards as other Germanic peoples adopted the 7 week calendar model. There is no evidence that it was very specifically holy towards Thor. We also don't have much evidence for it being especially sacred to Jupiter either. It was just a name for the day, which had lost all holy meaning by the 19th century.

-Regarding her point on travel: People travelled a fair bit in the past, including in winter, for example for Christmas. So it's not this sort of impossible endeavour like she makes it seem, especially since, if it was to visit family, a lot of people would live relatively close together in a community as opposed to the current situation where families might easily be spread out accross the country. The actual quote there is important as well: Hale's point is that people aren't travelling all over the country like in summer, but sitting at home with their family, or at least in close range of their family. That's a good time for a family holiday, especially when combined with all the food being in from the fall harvest. It doesn't point to anything pagan.

-We have two sources describing an Alfblot (neither from England.) One describes it as happening in the secrecy of the home, with no outsiders allowed. The other one describes the slaughter of a bull over a mound where the elves were said to dwell. Neither involves a matriarch in any specific role. Neither bears any resemblance with current day thanksgiving, except maybe the family element. But then again, families getting together for a religious holiday is a thing in... well every religion in the world. So that doesn't point to anything either. While we're at it, there's no connection between the Alfblot and Thor/Donar. In fact we don't quite know when Thor's holy days were, if he had any (and this is where it's also important to point out that local traditions around pagan worship and gods would vary considerably, so you can't extrapolate from a few Scandinavian sources to England and then America) Finally, I'm not very well versed in the state of international scholarship on medieval Norwegian literature in the middle of the 19th century, but I doubt Sarah Hale was very well-versed in that subject either. So I doubt she was even aware of this ancient holiday.

-She seems to make a big point that a holiday likes thanksgiving has to necessarily involve giving thanks to some god, but I don't see how that's at all necessary.

-The hearth was a common place of importance in the 19th century household. It was the centre of the house, where the family would congregate at evening together. It was also the women's space, where she would sew and knit etc. For someone like Sarah Hale, who despite her writing career was still very insistent on men and women having traditional roles, with women important in the domestic sphere, it would be very natural to emphasise this aspect of a family holiday she wanted to launch. You might think this is at odds with the whole depiction of her as a proto-feminist, but it's important to remember that a lot of women in the 19th century saw their worth in their particularity: they shouldn't imitate men, because they weren't men, rather they should demand equality based on their natural skills, like taking care of the household and children. So basically, for Sarah to put the Hearth in the centre of this family holiday is not at all surprising for her.

-Perhaps the references to Demeter and Ceres are explained elsewhere in the series, but I just want to point out that there is zero connection between these two deities and the various forms of Germanic paganism.

-She does not seem to understand how pagan rituals work honestly. The god needs to actually be involved. You sing hymns, do dances, say prayers and invocations, burn or kill sacrifices, etc. That's not present in any part of thanksgiving. The animals are not killed in any ritualistic way (in fact most people don't kill their own animals), any prayers involved are usually christian, no pagan gods are invoked. The only thing even remotely close to pagan sacrifices is having a meal together with other people, which was often done with the meat afterwards in various pagan traditions. But hey, by that logic I'm having a pagan ritual anytime I go to a restaurant with my mom. Thanksgiving has none of the elements of an actual, pagan, religious ritual. If Sarah Hale had the intention to reintroduce a big pagan religious ritual, it's safe to say she botched it spectacularly.

-Regarding the oak leaf thing: I'm not American but I asked my American friends. They don't know any oak leaf imagery that shows up for Thanksgiving. Perhaps it's a regional thing, but if it's such a small part of the holiday that several people who celebrated could not even know that there were oak leaves involved, that kind of weakens that connection. And also, since pretty much all the other connections with Thor or Jupiter are pretty much nonsense, I think it's safe to say that the isolated element of a particular leaf being common isn't exactly a smoking gun that proves the connection. Especially since oak leaves have the advantage of being pretty uniquely shaped, so they're good for decorations trying to mimick fall leaves.

Okay, let's summarise. Thanksgiving has no elements that show it as a pagan ritual. The connection with Thor is pretty much non existent. It bears about as much similarity to an Alfsblot as an apple does to a porcupine.

Now what's more likely: that this woman decided to try to introduce a completely bastardised, barely recognisable as such, ritual to pagan deities for what doesn't seem like any gain (especially because it fails to include any of the benefits that such a ritual might have given to the deities involved),

or that Sarah Hale was an American nationalist, living in a time where the country was being torn apart by tensions over slavery, so she wanted to promote a nationwide holiday honouring a part of the nation's founding mythology?