I still believe that the girl was under control in a few seconds after she got into the car.
1. looking at the footage carefully, 47", she opened the door and got in, frame by frame, you can see a white area which I think it's her face, and background is black which is seat
2. at 48", there was one guy rode a bicycle, and there was one while car approaching from behind.
3. when bicycle was close to stop sign and after stop sign, the white spot (her face) was gradually gone, it changed to black color.
4. at 52", perp started moving car, by that time, I believe she was already on the floor of passenger side
5. at 1:00, we can't see her on passenger seat, and the perp was looking down.
6. so I believe that perp knocked her out between 47" to 52", and he had plan on how to knock people out quickly, probably he got some kind of training or he is not first time to do this.
7. driving from that bus station to one north only takes about 3 minutes(by google map), to control an adult while driving is impossibe, specially on a two-lane road like that with traffic. I think perp knows that.
8. to convince a chinese girl to get into his car is not easy, I think he is clean, well trimmed, short hair by picture, smiling and convincing facial, no any visible tatoo, fit, and a normal person by first impression.