The workspace's YouTube allowance (new terms): video per period, used,
left, the per-video maximum and the playlist size. allowance is null on
the old terms (no limits); allowed is false when the plan has no
YouTube sources (Free), with the plan that has them.
Bearer <token>.Ok
The allowance as the preview and GET /youtube-source/allowance return it.
When the monthly allowance starts over; null for the trial.
0: single videos only (the trial).
Whether the previewed import fits as it is (true without a preview).
Why it does not fit (or why the balance does not cover it), in the user's words.
The plan that allows more, or null.
A playlist that does not fit: the first videos that do, which firstFittingOnly imports.
Playlist videos skipped: longer than the per-video maximum, or without a duration.
The AI balance does not cover the estimate (the import is refused until it does).