You can see the square in the background of the video, there's just rows of bicycles.
The whole "all the protesters were herded into the square, machine gunned, then homoginized via tank and washed down a drain" is a fabrication.
What actually happened, you can look up the gorey pictures and everything: Protestor groups 1-2 blocks away from the square lynch multiple cops, burning the bodies. Cops proceeded to drive around shooting civilians 1-2 blocks away from the square. Multiple police trucks end up burned in the surrounding streets, its unclear whether they were killing people mostly at random or entirely at random.