KCast is a KDE Plasma 6 widget that lets you cast video files or youtube URLs to a Chromecast devices in your local network. It supports device discovery, local media playback via an embedded HTTP server, and drag-and-drop integration with browsers and file managers like Dolphin.
Kbtv is a TV viewer for KDE/FreeBSD. It supports BrookTree/Conexant BT8x8 (bktr) and Philips SAA713x (saa) based analog TV cards, and Philips compatible USB webcams (pwc).