No idea when. But Season 20 the next Blu-ray box set. Hours of extra convention interviews. Dozens of studio feeds showing complete takes and retakes.
A lot of different versions of The Five Doctors.
To be honest, it would mainly be The Five Doctors materials I'd be transfixed by.

https://youtu.be/NMgKaTU9-bQ the very good trailer that didn't appear in the box at the top.