That’s a great video. I’ll just add more bits of info.
Relevant detail: there used to be another language spoken to the east of Italy not too long ago, called Dalmatian. Specially associated with Ragusa, the merchant republic. Typically grouped nowadays alongside Italian and other languages of the Centre and South of Italy. Eventually replaced - by Venetian and Croatian.
There might have been more Romance languages in the area between Italia and Dacia, but they were likely short-lived. The video mentions why, around 6:20: the Slavic expansion southwards.
It’s also arguable if Romanian should be considered a single language, or multiple. And I’m not talking about Moldavian - I’m talking about Aromanian, Istro-Romanian, Megleno-Romanian etc. All those share a common ancestor with [Daco-]Romanian/Moldavian, from around the 10th or 11th century; for reference this is a bit before Portuguese split off from Galician, and around the same time that we could argue for the “birth” of Catalan as something apart from Occitan.
Speaking on those languages, it’s worth noting that Romanian isn’t the only commonly forgotten Romance language; the maps in the video show it, there are a lot of them. People mostly remember the ones associated with large Western European countries (Portuguese, Spanish, French, Italian), but remember - languages don’t usually coincide with countries. Italy for example has three Romance branches (Italo-Dalmatian, Gallo-Italic, Southern). In special, Southern (nowadays just Sardinian varieties) is so divergent that it’s easier to lump the “four often listed” languages together, as “Continental”, than it is to lump any of them with Southern.
But I digress. Back on Romanian, there’s another hypothesis for its origin, that would be a migration eastward; Wikipedia mentions it. I’m mentioning this mostly as further info, as I don’t really take it too seriously, due to the absence of toponyms in the former region that would tie it with Romanian. (For comparison: London and York still have evolutions of their former Roman names, Londinium and Eboracum. And the later is not even Roman in origin, but Brittonic. As in, you expect leftovers of placenames, why aren’t they there?)
