As medical staff rush up and down, a loud groan of pain can be heard from the front of the plane.
In a second Instagram story, medical equipment can be seen blocking the aisle.
Along with the video, DJ Pavlin posted a message to his Instagram story saying: “At the start of the flight he [Navalny] went to the toilet and he didn’t come back.”
“He became very ill and they could barely resuscitate him as he screamed in pain. They are not saying what is wrong with him. Now we have landed in Omsk. An ambulance came.”
Earlier, DJ Pavlin had posted a photo of what appeared to be Navalny sitting in a cafe in the airport.
Navalny is currently in a coma in the intensive care ward of a hospital in Omsk, Yarmish tweeted, adding that there was a heavy police presence.
“The intensive care unit is full of police officers. They try to get an explanation from the doctor. The doctor saw me in the distance in the corridor, said that ‘some things are confidential’ and took the police to another room,” she wrote.