[rai] fix unavailable video format detection
[rai] fix unavailable video format detection

ozburo/youtube-dl,rg3/youtube-dl,Tatsh/youtube-dl,spvkgn/youtube-dl,yan12125/youtube-dl,ozburo/youtube-dl,Tatsh/youtube-dl,yan12125/youtube-dl,spvkgn/youtube-dl,rg3/youtube-dl