You just watched a creepypasta. In the beginning, that lady was driving past a crime scene where a man was seen disgruntled and, from the looks of it, denying an accusation about murdering his family. A few blocks later, the lady met her doppelganger and they had a fight. Doppelganger wins, and the lady was replaced. Doppelganger kills the lady's family and in the end it was seen that the lady was left there at the scene of the crime to take all the blame.
For all who is wondering, this is satire of medicine, basically. It says how much it could help you, and then it goes into the side effects, of which there are so many that you might be left worse off than you were originally. That part of the video is the last 8:00 minutes, basically. Although, there are a lot of different theories explaining what's going on here, so, I suggest you check that out.