IMO you guys (as well as whoever did that) are underestimating the difference in how the two different kinds of submission affect resulting discussion. I did offer to change the top URL to point to the video, if they felt that was more important, but never heard back.
How many hours had it been between them making that change and you updating the URL again, though? If linking to just the PDF v. a homepage with the PDF + presentation + code would affect the resulting discussion, it's probably fair to say that the resulting discussion has already been affected (this particular conversation notwithstanding), no?
Even that aside, if the authors care so much about what people see first that they actively set a particular URL to redirect to their preference (EDIT: and have explicitly stated that preference in these comments, assuming "apavlo" is Andy Pavlo: https://news.ycombinator.com/item?id=29939332), should that preference not be respected?
IMO you guys (as well as whoever did that) are underestimating the difference in how the two different kinds of submission affect resulting discussion. I did offer to change the top URL to point to the video, if they felt that was more important, but never heard back.