At 4:58, before shooting, one of Chinese soldier said:"da le,da le"(打了,打了). "da le ,da le" means "enemy fired, enemy fired". It's a proof of Vietnamese shot the first bullet( Which seriously wound a Chinese soldier's arm). Yet the author of this video intentionally translated "da le, da le" into "attack, attack", which totally distorted the fact and misled the those non-Chinese speakers to believe it's Chinese soldiers who fired first. How mean is that!
No matter whether the creator of this video has got a point in his allegations, he has surely lost a lot of credibility just for deliberately mistranslating 打了,打了. Full stop.
Just my two pennies worth.