See my answer in the other thread re: WACZ.
Yes, open in new tab should work. There is a Chrome bug that I believe stops recording in all tabs when any tab is closed (it is documented here, but unfortunately does not seem to be addressed: 1184643 - chromium - An open-source project to help move the web forward. - Monorail)
Re: Soundcloud, can take a look at soundcloud, it may be possible load the entire stream automatically (similar to youtube and vimeo), but requires some investigation.