How is youtube transcription feature reliable

Hi, i want to use youtube transcription functionality on my website to provide this functionality to end users.i have some questions though, could you please provide me some information regarding:
1. I need to use
// Get transcript from any supported platform (YouTube, TikTok, Twitter) or file
const transcriptResult = await supadata.transcript({
or
// Get YouTube transcript
const transcript: Transcript = await supadata.youtube.transcript({

2. What is the percentage of youtube videos that will return me transcriptions? (in english)
3. What happens if there is no transcriptions for the video?
4. the pricing will be always 1 transcript = 1 credit ? Or also a 1 generated transcript minute = 2 credits is possible? for youtube videos?
5. If queue is started to get video transcriptions - how long it takes?

So basically - what is the approach you can suggest me to use your api, to be able to calculate the token usage and be sure the customer will get it’s transcription in reasonable time?

Thank you.