Network Monitor fails to download some YouTube videos. Check
http://applian.com/replay-media-catc...ernet-settings.

I am not on a VPN and I don't really know what that is, I was using the wrong network driver. I am now using WinPcap.

The problem occurred because WinPcap was installed by Replay Media Catcher 5 installer, but the option was not checked in the settings and couldn't be checked, which lead me to install Network Monitor. I needed to manually uninstall WinPcap (and Network Monitor) from Windows 8 Programs and Features, restart computer, start Replay Media Catcher 5, go to Settings, and reinstall WinPcap. No need to uninstall Replay Media Catcher 5.