Yes don’t worry too much about it, there’s a lot of little things that come into play when messing around with render settings. In the video there could’ve been lots of tweaking that wasn’t shown, like light bounces or light portals, not to mention updates on Blender itself. The power of your light, how close it is to the wall, etc., it all plays a part. For the noise in your scene it also depends on various things, you’d have to have an exact replica of the scene shown in the video to get the exact same results. In the end, the important thing is that you learn what it all means, to read the information the viewport shows you, know about color management and how it can affect your final results so you can apply it all to your own renders.
