I noted one sign that was from the marginal, purportedly ultra-Orthodox Neturei Karta group (NKUSA) - but the person we could see in the video holding the sign was clearly not a member of Neturei Karta, whose members dress all in black as if they were normative ultra-Orthodox Jews.
Apparently, Neturei Karta hires some non-Jews to protest for them, presumably for the Sabbath.
And according to Jewish law, this would not be allowed. Jews are not allowed to hire non-Jews to do activities for them specifically on the Sabbath that Jews would not be allowed to do themselves, and carrying a sign in Manhattan qualifies as such an activity.
It should be re-emphasized that every other ultra-Orthodox group has condemned Neturei Karta, even other anti-Zionist sects.
If this rally really was on this past (or any other) Saturday, Neturei Karta is breaking Jewish law. If not, then Neturei Karta is hiring people to protest on its behalf.
UPDATE: Edgar Davidson has seen Neturei Karta directly violate the Sabbath last month in British "Al Quds" rallies, carrying banners in Trafalgar Square. Others have observed the same.