I saw the whole trial, and watched the video frame by frame several times. That is what I saw. The video does not show Miu's hand when it jabs, just his arm going forward. Ryley holding phone up. But, as he pulls away it shows knife in hand. I guess we disagree.
Calling someone names should not lead to murder. Especially when it is a bunch of immature drunk 17 year olds. He should have walked away. Just how many times was he asked, demanded to leave where the boys were. He went out of his way to get close to the boys. I suspect he did not like a bunch of noisy boys hurting his peaceful river trip. Though he could not have predicted the final outcome.