When we did our night ride on that first soft opening day, we decided to scan all the QR codes while in line, which just took us to behind the scenes YouTube videos. Not once did we see a single other person scanning the QR codes and watching the videos, and quite frankly, I don't think people even realize that the plaques around the queue are QR codes. I think Universal overestimated people here.
When we all first heard that the queue was going to be a celebration of stunt work/behind the scenes stuff, what I imagined was video screens along with the props/stunt cars, of stunt crew or producers or the actors talking about things so people in line could watch, similar to more of the "old school" Universal style; asking people to not only realize they should be scanning QR codes, but to then watch videos on their phones in an already loud and crowded environment seems counterintuitive, as people are far more likely to collectively watch screens in a queue than they are to be motivated to put in work scanning for YouTube videos and draining their phone batteries.
That said, I also think most parkgoers just... don't care anyway. They're focused on the coaster going on above and around them, as well as their own personal conversations, and even if there were screens about the behind the scenes stuff, the majority would undoubtedly talk right through them anyway, so maybe Universal realized from the get-go that there's no point.