The legality of recording a video stream you can watch on your PC is very dependent of your country. I think it should be legal as long as you keep your recording for your personal usage.
I agree, and the ethics also depend on what you're doing with the video. IANAL so I can't comment on legality.
I download some conference videos from YouTube to watch on my train journey. I can't stream them because reception on the train isn't good enough. It's the only place I can find the videos (they're not available for sale) and I don't share them with anybody afterwards.
I don't consider that to be unethical, and I don't imagine the police are going to hunt me down.
