Videos without captions
Videos without captions fail as no_captions and are never charged. Manual and auto-generated captions both work; there is no audio fallback.
What happens
The job goes to failed with error no_captions and nothing is charged. There is no transcription fallback: speech-to-text was tried and taken out, and it is not offered today.
Detecting it early
If you are building a list of videos to process, treat caption availability as a filter at collection time rather than discovering it one job at a time. In a large batch, expect a small percentage to drop out this way and make your pipeline tolerant of the gap rather than treating it as an incident.
Charging
Never charged, and it shows separately on the usage screen so a run with many caption-less videos is visible rather than silently eating your allowance. Retrying the same video will not help unless the channel has since added captions.