Do you guys agree with this?
Hi, I don't generally watch that sort of thing on YouTube so don't really know what they're saying.
But a few things you should know about color films. They're made with three different color layers, each sensitive to certain colors. The sensitivities are only matched under the correct light, which is generally "standard" daylight, which is about the same as electronic flash. So if you want a so-called accurate exposure it should be under one of these lighting conditions.
If you use different lighting there's a good chance that at least one of the layers will be underexposed. For example, consider the old style tungsten lights (the sort of light bulb that gets hot). Such a lamp is weak on bluish light relative to reddish and greenish light. In fact, compared to daylight, the bluish light component is only about 20% of the reddish light. If you used a daylight-balanced film like Portra under this lighting, the blue-sensitive layer would likely be underexposed by a stop or two, depending on how your specific meter sees things.
Next major point: color neg films typically include both hi-sensitivity and lo-sensitivity layers in each color. And the hi-sensitivity layers, like high-speed films, are grainy. What this means is that underexposed film is gonna be relatively grainy in the shadow areas. And if you have one color-sensitive layer that is underexposed then that color layer will give grainy results in the shadow areas.
What does this all have to do with you? Well, if you are in daylight lighting conditions then you should be fine exposing according to the meter. If the lighting is deficient in certain colors then you should increase exposure to prevent having one underexposed color layer.
Now, with respect to Portra in particular, my experience has been mainly with the 160 version (I expect that the 400 will behave similarly) under studios lighting conditions. And optically printed. In this situation Portra could go anywhere from about a stop underexposed to 3 or 4 stops overexposed, and if the prints are individually hand-balanced, the color results are so close that you cannot tell them apart. Anybody who is educated on the internet will probably find this hard to believe, but it was done (albeit 10 years or so ago) under very stringent test conditions. I described some of the testing here:
https://www.photrio.com/forum/threa...-of-color-neg-film.168506/page-3#post-2192714
Ps, you should not assume that other color neg films have the same exposure latitude.