Let's assume you have a dictionary called transcripts:

transcripts = { "first" : "~/docs/file1.vtt", 
                "second" : "~/docs/file2.vtt",
...
}

To iterate over all of them:

for transcript in transcripts.values() {
   yourFunction(transcript)
}

There are lots of good tutorials around - see https://www.geeksforgeeks.org/iterate-over-a-dictionary-in-python/