[core] Fix simulate changing format selection

[seproDev]

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Description of your pull request and other information

Fixes #9843

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[seproDev]

Is changing the signature of _default_format_spec by dropping the download parameter as done in 70ca5fb okay?
This function isn't part of the public API, so imo. it should be fine. Interested to hear what everyone else thinks.

[pukkandan]

Personally, I'd have added a deprecation warning anyway, coz I'm conservative with this stuff. But it's not really needed. Your patch looks fine.

But to clarify, my comment was not demanding we do it this way, but simply to give my opinion. We should try to have identical behavior with ytdl on this. So let's coordinate with dirkf on which is better.

[seproDev]

I agree with you in that I think it makes sense to change the downloaded=False behaviour in one swoop. That's why I added it to the PR.

[bashonly]

I also think it's better to have download=False behave as if simulate=True. @dirkf