Thank you for sharing the video.
Problem is that manufacturer is recommending 5w30 or 10w30 in the manual.
Also as per video we should follow OEM specifications which is 5w30 or 10w30.
1st number is the viscosity at ambient temperature and 2nd number the viscosity at Engine operating temperature. Engine operating temperature doesn't change much at different ambient temperatures.
We can change the 1st number according to ambient temperature e.g. 0w30 for server cold area and 10w30 in extreme hot area but the 2nd number should be the same.
Please correct me if I am wrong as this is my understanding and may be incorrect.