Teresa does not have Hillary’s broad back end, nor her Cankles, nor extreme edema in her feet. The double (whether Teresa or another) does not have the same hair, fingers, ear rings or jewelry.
Regardless who it was, it was not Hillary in the videos.
Now the question, what was the source of the videos? That would reveal what we actually saw.
Hillary left the 911 ceremony at 0930. She was AWOL for 90 minutes per her complaining media. Throw in travel time to get to Chelsea's, we're talking 11:30 before she walks out.
September NYC, sun is starting to drift south for the winter, but basically at noon it should be close to overhead, maybe 10 degrees off - ie small shadows. Yet look at the shadows here:
That's not noon - those are significantly slanting shadows. And if it's not noon, then when was this - early morning, BEFORE the ceremony?