"Iranian security forces deployed unknown chemical substances amid deadly crackdowns on protestors in several cities earlier this month, eyewitnesses told Iran International, causing severe breathing problems and burning pain.
They described symptoms that they said went beyond those caused by conventional tear gas, including severe breathing difficulties, sudden weakness and loss of movement...
...According to the accounts, in some cases gunfire began at the same time, or immediately after, protesters lost the ability to walk or run and fell to the ground.
Several witnesses said that moments of immobilization became points at which shooting intensified, particularly when protesters collapsed in alleys or while trying to flee.
Reports came from multiple cities, including Tehran, Isfahan and Sabzevar."
The footage was clearly released to potentially reveal these sensitive facts, as the local police were thusly trying to prevent carrying the blame for her death, by showing the parts requisite for understanding.
If you need a more detailed description just reply to this comment and I will give more detail analysis of the footage.