Just read about the incident of a driver hitting up a cyclist. This reminds me of one of my rare encounter with a driver.
I was cycling along Bukit Timah Road on my way to NTU on morning. At a junction along either Upper Bukit Timah or Jalan Jurong Kechil where I needed to ride straight, I turned and check the traffic behind. A car was behind. I observed for about 5 seconds and since there isn't any ... left signal light blinking, I continued riding forward. Then, I noticed the driver actually wanted to make a left turn, and he tried to make the turn in front of me. I have always been angry towards such driving manner, and thus, judging that he was in good control of the car, I purposely and slowly continued riding across the front of his halfway left turning car, forcing him to stop and wait for me to purposely delay him.
Regretably, I also raised my hand, but not all fingers pointing up (I hope readers know what I meant :P) which made him very angry. He immediately and with high engine revolution rate, U-turned his car and cut me off slightly further up the road. He got off the car and angrily walked towards me.
Knowing that I was wrong to raised my hand without all fingers point up, I quickly apologized to him for my earlier gesture. Luckily, this worked and he seemed more calm and asked me why did I do that. I firmly told him that I was angry because he didn't turn on left turn signal before making a left turn, and furthermore making a left turn in front of me!
Surprisingly, he was satisfied with my answer, returned to his car and drove off. I was lucky he didn't beat me up :)
Retrospectively, I imagine what this incident was from that driver perspective. He was patiently, or almost running out of patience waiting for me before making the left turn. He noticed that I turned back and saw his car, and probably felt that it should be safe for him to make the left turn, and so he did. Then, shockingly, I seemed to purposely forced him to stop and rode straight ahead even though I knew he was behind me. All these might be just an insignificant encounter since there wasn't any contact, but my gesture made him very furious.
Thus, I think similar misunderstanding might have happened to the above cyclist, and it wasn't the misunderstanding, nor the almost but didn't occur accident, but the inappropriate gestures that had caused further risks.
That driver might have expected the cyclist to give way, and became very angry and turned aggresive to defend himself and his supposingly weaker passengers, who may be his family, since to him, it might have seem like the cyclist was challenging him down to clash it out.
I learned that to remain calm and courteous on road, normally or otherwise, is very very important.