You're technically correct, it would add up to be equivalent with enough scale. However, given the stats I've seen from solar panel owners about how much electricity their computers/phones actually use compared to charging up their car (with the former basically being a surprisingly tiny drop in the bucket compared to the latter), the number you're looking for to make a comparison might still be at least an order of magnitude higher than you expect.
My point really was about scale. Put some wasteful code in some rarely used application and it means nothing (the proverbial drop in the bucket). Put the same thing in a very popular app or library which is used by millions (or even billions); then it is a whole different story. It seems YouTube fits this bill. But because the collective cost is spread across all the users; no one is pressed to fix it.
Another recent claim [..] estimated that 7bn YouTube views of “Despacito” [..] had consumed 900 gigawatt hours (GWh) of electricity, or 1.66 kWh per viewing hour.
At this rate, YouTube – with over 1 billion viewing hours a day – would consume over 600 TWh a year (2.5% of global electricity use), which would be more than the electricity used globally by all data centres (~200 TWh) and data transmission networks (~250 TWh).
It is clear that these figures are too high – but by how much?
It should be perfectly clear that the client-side impact of this transfer is not important, since a mobile device still loads YouTube embeds instantly, but does not burst into flames while doing so, as it necessarily would if the energy cost was as high as the other person is suggesting.
Sure, TBH I was inspired by your comment that "there is a person whose full-time job is to consider the energy usage of YouTube in all its aspects" and figured I'd throw in an IEA commentary from someone who watches the watchers.
It's a big picture look at youtube energy use, but hopefully of tangential interest.
This is not one of those things where a long tail dominates. You could transfer a megabyte of data over Wi-Fi to a portable device 20 million times with the same energy that you need to charge a standard range Tesla once. Furthermore, I can assure you that there is a person whose full-time job is to consider the energy usage of YouTube in all its aspects.
