What is the mechanism for demercuration? The following image is from 'Organic Chemistry Second Edition' by Clayden, Greeves, and Warren.



The final step is the demercuration, but I'm unable to find a definitive mechanism.

The wikipedia page lists a mechanism sourced from the Journal of the American Chemical Society:

Wikipedia Page for Oxymercuration

But I've found videos on YouTube which outline an SN2 displacement of the acetoxymercuri group by hydride. e.g.: Mechanism of Oxymercuration Demercuration (new)

So I would like to know which mechanism is correct.
Apparently, the current assumption implies formation of $\ce{R-Hg-H}$ intermediate, followed by radical chain decomposition This, however, should be taken with a grain of salt, i.e. very skeptically. Proving mechanism is an incredible amount of work, and considering relative unimportance of organomercury chemistry in modern organic synthesis, it is unlikely any considerable resources will be allocated to the task.