Hi:
Your rationale here is decent, but you run the risk of trampling all over copyright issues. And ending up in a legal soup as a result.
Giving credit does not absolve you of profiting off someone else's creation. And just because it's available for free doesn't mean there's no copyright protection.
Sorry.
Given all of that, consider a pivot for your business idea that involves working with the creators of these videos and podcasts to generate transcripts.
If you wish to discuss, send me a PM through Clarity for 15 free minutes.
Cheers,
Kerby