Castmate
Chromecast connects but the video doesn't play
The TV shows the cast screen, then nothing, an error or a spinner. Here's how to find out why and what to do.
When you cast a video (not a whole tab), the TV doesn't get the picture from your computer. It gets the video's address and fetches the stream itself. So the TV connecting is only half of it: the TV also has to be allowed to open that stream, and be able to decode it.
1. Is it protected (DRM)?
Netflix, Disney+, Max, Prime Video and most paid services encrypt their video with DRM. Only their own app or the Cast button inside their player can play it. No extension can, and shouldn't.
2. Does the site only give the video to its own page?
Many sites check where a request comes from (the Referer header, a cookie, or a signed link). Your browser passes those checks; the TV, asking on its own, gets refused (an HTTP 403). Signs: it fails on one site but works on others. The fix is to let something on your computer fetch the stream for the TV with the page's details. Castmate does this with its relay (a small Mac app, not released yet).
3. Has the link expired?
Stream addresses often carry a time limit (expires=, deadline=). If the page has been open for a while, reload it, start the video again and cast again.
4. Can your TV decode it?
Every Chromecast plays H.264 video with AAC sound. HEVC, VP9 and AV1 need newer models. If the site offers qualities, pick a lower one (often H.264). Paste the playlist into the stream inspector to see its codecs.
5. Same network, nothing in between?
The TV and computer need the same Wi-Fi; guest networks and VPNs on the computer often block casting.
Castmate for Chrome checks these for you when a cast fails and says which one it is, with the next step: try another route, reload, or report the site.