Find something you agree upon. You could appeal to her energy saving mindset.
For example mention how much power an always on computer is drawing and say that videos use CPU which ramps up the wattage and usage. Bright monitors use more energy than dim ones etc. Sleep mode vs always on.
If you want to go even further you could mention the carbon footprint of youtube and internet servers but this is pushing it a bit.
Sometimes we need to accept insanity in our friends and partners. My wife does stuff that I used to hate but now I just accept that’s how she does that particular thing. As a society I think we care too much about people doing certain things the right way.
a good example of this is having a massive number (50+) of tabs open in your browser ... I think that's completely unusable, but I've worked with other techies who do this, and also seems to be a common thing here on HN. Another example is having tons of stuff all over your desktop.
Ahaha, you think 50 is massive? I have over 20 browser windows open, and several of those windows have literally hundreds of tabs. At various times when I've done an actual census (usually before my every-few-years purge) I've had 700 to 1500 tabs. I'm not saying you should like it or emulate me or whatever, but I can't understand what you could possibly be thinking when you say it's "unusable".
Of course, many people use browsers that can't handle it. That would make it literally unusable.
I've just tested letting a Youtube video play on my M2 Macbook Air.
At 25% screen brightness, it uses around 4 Watt.
At 50%, around 6 Watt.
At 100%, around 11 Watt.
The person in question is unlikely to have a modern computer, but letting a video play all the time could technically still be using less power than the light.
That's insane to think about. Extrapolating down to 0% brightness means the actual compute required to manage the network connection and decrypt and render the video, plus anything the OS is doing in the background happens in maybe 2 watts?! With 2 watts you could power a fairly dim LED lightbulb or perform the equivalent of thousands(?) of man hours of hand computations.
Trying to come up with post-facto explanations which arent your true reasoning in order to manipulate your partner's behavior is a huge red flag. If you follow this sort of advice in your own relationship it is very likely going noticed and dissolving trust in your relationship.
Using a different then my own true reasoning is completely normal, and everybody does this. One adjust your reasing to the understanding of the other person for example. Moreover, there is like a miles wide gab between rhetoric and manipulation.
It is perfectly fine to present alternative reasonings to convince someone of something as long as you don't pretend that reasoning is the basis of your own position.
For example mention how much power an always on computer is drawing and say that videos use CPU which ramps up the wattage and usage. Bright monitors use more energy than dim ones etc. Sleep mode vs always on.
If you want to go even further you could mention the carbon footprint of youtube and internet servers but this is pushing it a bit.