I will watch it now, but
If he did not mention the antibody testing in those patients over time, AND
did not use live viral cultures in addition to PCR testing of RNA remnants, then he is not using all of the tools in his toolbox.

Smart people speculating is still .... speculating.

Absence of evidence is not evidence of absence.
And antibody testing and live viral cultures are the evidence needed here when you are declaring that exceptions to the rule exist.

If these patients are still antibody negative or are unable to produce IgG's to take over for their IgM's, then that is a potential explanation but that is on the patient, not the virus why that happens.

After watching the video, what I said above still holds. They need to really do more to assess these relapse patients.
You can also do a PCR test for sgRNA which can indicate rapidly replicating virus and "infection" rather than remnants, but he is not doing that or live cultures. Just doing the same PCR test as a test of cure. I don't think it should be used as a test of cure. No fever for 72 hours off all meds might be a better indicator of recovery plus presence of antibodies.

I was glad he did not discount that immunity should give protection to the people involved. if that was not true, then convalescent serum would never work, and that is having success in cases thus far.

Nothing in the video is scary in my opinion. All viruses and bacterial infections are scary if all you look at are the outlier cases. Contagious things throw a lot of outlier cases all at one time.