CDN-server | placeholder text - | Data Manipulation library

The problem is just: the response from https://v.redd.it/5r0nz8sywgl41/DASHPlaylist.mpd to the GET request from your code doesn’t include the Access-Control-Allow-Origin response header. Strangely though, it does include the Access-Control-Expose-Headers response header. So the cause is just that the server is misconfigured; it’s not actually properly CORS-enabled.

Specifically: even though the server sends a Access-Control-Allow-Origin header in response to the OPTIONS preflight, that on its own isn’t sufficient to make browsers allow your frontend code to access the response to the actual GET request in your code. For your code to work, the server must also send the Access-Control-Allow-Origin header in response to that GET request too.

But you can actually work around the https://v.redd.it misconfiguration and access Reddit HLS/DASH URLs from your frontend code without needing a browser extension — by making your request through CORS proxy, as in the following example.