Not about Viet Nam, but still relevant.
Back in 2000, I encountered a civvie who was working in the Australian Army compound in Dili (East Timor). He mentioned the following:-
The Australians regularly patrolled the border (No, it wasn't Viet type thick jungle). They were concerned by Indos following and taking pot shots to harrass. I believe no casualties, just harrassment. So one day, the SAS followed a safe distance behind our patrol. The problem was removed. SAS still knew how to be invisible. The problem never reocurred. The incident was never reported.
Aside from Youtoob BS, there are believable reports by American vets, to support those Vietnam stories. Mainly they highlight the arrogance & poor training of the US military.