Something similar happened to me way back when driving my good ol' GTI. All I heard was a pop, tire went to shreds. As far as speculation goes, I had to have driven over something sharp at lower speed, before joining the motorway. Sharp to cut enough into the tire to create a weaker spot but not deep enough to completely split the tire on the spot. As tire heated up with rotation, the weakened spot eventually gave up and popped open, shredding the tire. Obviously, just theory but the tow guys were not able to find anything at the spot when the tire shredded, so no nails, or anything on the roadway.
Never happened again to date but it was pretty scary at the time.
Now, recalling how the car pulled onto the side, I am really glad nothing happened to you and the car seems to have survived as well. eTron is much heavier so much harder to predict how it behaves when a tire goes out.
Also, not sure if you can blame whoever installed tires. Do you have tire warranty on them? This can be submitted as a tire damage under warranty, I was lucky enough to have it on GTI ones, so I got a new pair at the time.
EDIT: looking at the video closely, it seems that something happened on the overpass section, at least that is where I can hear a low thud. You might have hit one of the surface holes there, but it is just theory. I did not see tire fragments right at that time, but shortly thereafter I noticed vibrations, to likely air evacuated and you started running on a flat. After that, you can see tire shards. The video quality is obviously hardly sufficient to notice much at the speed.
