It is true that the histogram shows exposure for jpg (naturally, because the raw file is not an image yet). But that does not mean it is useless, on the contrary. It just means that you have some more "headroom" with a raw file. Even if the histogram starts climbing a little bit up the wall, you can still recover some blown out highlights, at least some of the colours. The RAW file has a much larger dynamic range than JPG, and can take more adjusting in post-processing without cracking up. You can not expose to the right without watching the histogram, it wil just end up in overexposure and blown highlights.
Do not trust any random video on youtube, there is lots of false information