They aren't calling into question the clip's credibility; they're saying its potato-quality audio literally sounds like a deep fake.
- This isn't happening
- It isn't a big deal it happens all the time
- He probably didn't say that it isn't a big deal that happens all the time, it reeks of a deep fake
- He didn't say it is a deep fake, just that it reeks like one, but isn't
There's also no apparent reason to doubt its authenticity, given that Yahoo Finance is a reasonably credible source and the content wasn't particularly outrageous.
- The only outrageous thing about that video are the audio distortions which were probably not caused by a deep fake, as we helpfully explained to you
Thanks for clearing it up! My bad.