Good on you for putting a video up with a thorough explanation, trouble is, the same airheads will be asking the same ridiculous questions day in day out, one can only hope they get banned soon enough
Apply at HCMC they're a bit more forgiving and will let you know what documents they want if needed. Don't listen to the tin foil hatters here about "local employment" and "permission" etc.
Got mine back in February (workcation route) in Vietnam and they were really thorough but fair. They verified my employment etc but if they were stricter I still wouldn't mind. Only ones complaining are usually the dosser backpackers trying to squeeze on the soft power Muay Thai or cooking class route 😅
Just doss out and chill with a beer 🍺 and forget you even did the application. I did it whilst in Da Nang and just got lost on the beaches and hiking etc and totally forgot about it until I got the approval email