Presumably this just tells the Chromecast to stream that video from YouTube directly. But OP's problem is that this doesn't work well for some specific videos.

Presumably this just tells the Chromecast to stream that video from YouTube directly. But OP's problem is that this doesn't work well for some specific videos. So OP is using catt not just to send a video URL to the Chromecast, but also to actually serve the content.