With requests like this generally theres more to it. ie the person is actively using a VPN , suspected fake documentation/prior bans etc.
It may seem extreme but documentation is easy to fake these days so asking for a selfie outisde your house etc(which they can confirm via google streetview etc) when there is suspicion is a new thing thats becoming a more common request. I don't see how them holding such an video/image is any more dangerous than them holding your unedited ID/bank statement which they can do alot worse with if stolen.
As for not taking a selfie in your home etc for the video I don't see what the issue is, tell the casino that and see what they say? It could be a metadata issue(ie if the metadata indicated you were in another country/area than your claimed address).