Supposedly it’s not yet dead… though as you pointed out it hasn’t been updated for quite some time and its successor has been around for quite some time as a preview (Plex HTPC).
I just unearthed my install to reproduce your experience. The app had some hiccup getting the stream going on the 1st go (endless spinner, so I had to stop and go back to the home page) but everything streamed as expected and immediately afterwards. So I guess it’s still working.
