"How do you know it was buy and not a sale?"
It is not difficult. Look at the previous trades and the following trades. They are priced lower:
16:17 $ 35.21 150 16:11 $ 35.163 330 16:09 $ 35.17 150 16:08 $ 35.5695 200 16:03 $35.3397 10,800 16:03 $ 35.3451 3,070 16:01 $ 35.3467 809 16:01 $35.3467 15,058 16:01 $ 35.3467 12,426 16:01 $ 35.3467 985
16:00 $ 35.17 100 16:00 $ 35.15 100 16:00 $ 35.20 100 16:00 $ 35.20 451