"Expose to the right" does not just mean overexpose on top of your meter reading -- it means using the histogram to make sure your information is towards the right side of the range but that you aren't clipping anything, or anything important (a tiny glint off of a metallic surface can be clipped.)
Truth is that while it works for still photography, it's only a rough guiding principle in cinematography -- the principle being that it is better to not have all of your picture information on the left end of the histogram (underexposed) except for certain scenes or moments.
The trouble with the ETTR principle is that it ignores an essential element of cinematography, which is continuity between shots within a sequence. You don't expose every shot as if it were its own scene or like you would in still photography -- a shot has to be intercut with another shot and it has to have a consistent noise level, saturation, etc. The subject in the scene should look like it is in the same light level even if the camera goes wide or tight.
For example, imagine a wide master of a person sitting at a desk with a table lamp next to them on their right and a big daylight window on the left side of the frame. Then imagine the medium shot no longer has the bright window in the frame but still has a slightly less bright (compared to the window) table lamp in the shot. Then imagine a close-up of the actor where there is no window and no table lamp in the frame.
If you were using the ETTR principle, then your exposure on the wide shot would be determined by the bright window (and the face maybe many stops underexposed as a result), in the medium shot by the bright lamp, and in the close-up by the face. So the face in all three angles would be exposed differently -- in fact, the close-up might look overexposed if the face was the only object and it was pushed to the right side of the histogram. You'd end up creating a lot of work for yourself in post trying to make the shots match each other so they could be intercut.
So the principle applies but only loosely in that for the wide shot, you'd want to expose for how you want the actor to look but if the window is too bright, you'd work on bringing it down with ND gel maybe or even an ND grad on the side of the frame. You may also slightly stop down to hold more window information. But also atmospherically maybe the scene should look like the actor's face is a little dark because most of the light comes from behind them. So when you get to the close-up, you'd probably continue the underexposure... but maybe you'd slightly open up to get a little more exposure on the face. But in general your exposures are all within a close range so that the three shots are intercuttable.
Also remember that your final image won't be shown in log gamma, it will be converted to the display gamma you will be showing the image in. So the blacks will be black instead of milky grey as with log. I'm only saying this because some people looking at log images get freaked out that they are seeing noise in the shadows but when the image is shown with the correct display gamma, a lot of that noise is hard to see.