When なかなか is used with an adjective or noun, the speaker expresses a sense of UNEXPECTEDNESS or SURPRISE.
In this case, the Meaning is "QUITE", "PRETTY much", or "MORE THAN I IMAGINED".
The adverb なかなか is used with an adjective in its AFFIRMATIVE form to convey a feeling of being impressed or more than you expected.
In the case of nouns, it's formed like this: なかなかの(adding の)+ NOUN.
This grammar form belongs to JLPT N3, but I wanted to explain it to you here because we've already covered なかなか~ない, which is related in the previous video.