BBC har gått igenom filmerna ordentligt.
https://www.bbc.com/news/world-europe-65178332
"So we took a screenshot of the woman and used facial recognition software to compare it with an image of Ms Trepova from her VK account."
"We got a similarity score of 96.3% when we ran these images through Amazon Rekognition. Another piece of software, concluded there was a "high probability" they were the same person. "
"In one edit of this footage the screen immediately then goes black, and an explosion is heard - suggesting it came right after her gesture and while she was speaking to him.
This was what prompted the speculation from social media users.
But the video was edited at this point and we've found evidence that the explosion did not happen immediately after she covered her mouth.
We found another video of the bombing, uploaded by the '112' account on Telegram - the Russian messenger app.
It shows the exact moment of the explosion. Seconds before, Mr Tatarsky is in conversation not with Ms Trepova but with a man in the audience. "