The idea of the small image over blurred background is to make the low-quality image smaller on a moder large screen, like it would have been on a small CRT back then and yet to keep the screen visually filled like in the original documentary. Then the idea extended into using the same thing for the film footage to make it visually consistent and again fill the screen, like the original documentary’s Pan&Scan footage. And finally, I added the extra horizontal blur under the BTS footage to simulate the same AR as the film footage. I personally really like the look.

As for adding a bit of dirt to the Indy (and 2010) footage, I wanted to preserve the feel that the original documentary had, where the film bits just breathe celluloid even through the layers of analog noise, so I used the film scans for Star Wars footage and I wanted to give the footage where I had to use Blu-Rays similar feel - I even regraded the Indy footage closer to the way it looks in the documentary.