YouTube Tv iOS screen record

I’ve seen videos posted by any number of people on various platforms that have definitely been recorded via a screen capture that have recorded a specific clip from a current show.

I have an iPhone and a surface pro and use YouTube TV as my cable provider.

I’ve tried ti record a clip from a show on YouTube TV through my iPhone with the standard iOS screen recorder as well as a handful of apps but each time the recording ends up as a black screen with only the audio. Obviously YouTube TV has something set up as an anti piracy restriction.

Does anyone know of a way around this? Can it be done through an iPhone or is there a way through a desktop?