When I read the original article, my first thought was: wow, someone could or should really build an interface on top of this that let's you cast all things.
Looking at this GitHub project, looks like it lets you do exactly that.
Yep, I had the same thought a while ago, which is why I built catt! It's come along very nicely, it works well and it's especially suitable if you run it as part of some automation (for example, you can make an Alexa skill to cast videos to your TV from various sources).
VLC also does transcoding of video formats that Chromecast does not support. For the python script, you have to ensure the video format is supported by Chromecast [1].
That's not the same. If websites don't implement a cast app themselves, then Chrome will just mirror the tab to the TV. Whereas catt and similar tools will actually direct the chromecast to download the video file directly and play it. This makes a big difference to quality and performance.
While this is true, newer Chrome versions have a feature where if you fullscreen a video in a tab, it will (within a few seconds, if the video is in a directly supported format) attempt to send the video directly to the Chromecast instead of mirroring the tab. It doesn't always work, but it's much smoother when it does.
That's nice; historically when i did that I'd lose the borders but quality would suffer. Admittedly i mostly did it with streaming content that was not CC compatible though.
So what you're saying is that it's probably better to use a browser, because your bandwidth between your PC and your TV is likely to be much better, as well as having the capability to cast not only web content but also anything on your desktop. Plus a mirror is much easier to control, and some cast capable devices may not have the memory to "download" video files.
What am I missing here? You seem to think it's a bad thing.
sending a video stream from a file on your disk on a computer results in higher quality video on the television than playing a video in your browser and encoding a stream of your browser window and sending that to the chromecast to display on the TV.