Use applications as video sources for apps like Skype? Is there a solution out there that can screen record 1 application and "stream" it through a fake virtual camera, so the video can be sent live through apps like Skype?

Just wondering if it's possible to, for example, stream a video playing in VLC/QuickTime through Skype, and be able to keep that video going through Skype even when I am doing other things on the computer.
Take a look at webcamoid, manycam, and Magic Camera and the corresponding VLC plugin.

Be aware the Magic Camera download seems to be bundled with malware and the VLC plugin is very outdated.

softwarerecs.stackexchange.com is also a good place to ask.