Airplay grey screen when watching DVD on MacBook Pro

I rented a DVD from Redbox and am trying to Airplay it from my MacBook Pro to my TV. I don’t have a DVD player anymore. I used to be able to do this without any issues but now there’s a grey screen. I read a previous comment saying it’s illegal to do this. Why? I legally paid to rent a DVD and watch it. This must be a new restriction with the operating system. I’m running Mojave. As I’m sure you know, the volume on MacBooks is awfully low so now I’m stuck watching this movie without being able to really hear it. Any suggestions besides not using DVDs?