She could have just denied it was her in the video. It is impossible to prove if someone denies it.
In Australia my friend identified a woman appearing clearly in a TV news bulletin being arrested at an anti-lockdown rally and complaining loudly. In fact it was official supplementary extended footage from the TV station uploaded to youtube: about 20 seconds of just her.
She is denying it was her though and is suing him for defamation. It has cost him over ~~US$100~~ US$100k so far and the hearing day has not even arrived.