To play the devils advocate here, What if the customer wants to have a blog series on how that product was built? Key software design decisions, features, etc. What if he wanted to run this video by another software developer who only agreed to do software reviews, etc. How different would this from recording a bunch of screencasts on building a product. The customer gets knowledge of the entire build process, from the initial sketches to the final release.
But most if not all of it would be too much to deal with for a freelancer and should at least incur a 3x price increase to deal with the various variables involved.
Seems pretty clear this was not the case, since they told him they didn't believe he was working. I think this is just another point in favor of NOT billing by the hour for contract work. If you are billing for the product delivered, rather than your time, it takes your work habits completely off the table.
But most if not all of it would be too much to deal with for a freelancer and should at least incur a 3x price increase to deal with the various variables involved.