The term tankie comes from the 1956 hungarian revolution/counter-revoluton (depending on who you ask) which split the British communist party, those that supported the Soviet Union suppressing it with the military were called tankies.
The video of the man in front of the tank column related to the June 4th incident did not result in the man standing in front of the tank dying, and those tanks were leaving the area where the violence occurred and is not where the word tankie comes from like I believe you are suggesting.