Try playing the first video here in Tech Preview: https://blog.gtk.org/2020/09/30/gtk-3-99-2/ It plays for maybe one second, then stops and cannot be restarted until the page is refreshed.
0:00:03.263991125 67 0x177e550 WARN webkitwebsrc WebKitWebSourceGStreamer.cpp:1058:responseReceived:<source> error: R2: Received unexpected 200 HTTP status code for range request 0:00:03.264413266 67 0x177e550 ERROR webkitmediaplayer MediaPlayerPrivateGStreamer.cpp:1871:handleMessage: Error 9: R2: Received unexpected 200 HTTP status code for range request (url=https://blog.gtk.org/files/2020/09/toy-convert-video-online.com_.webm?_=1) 0:00:03.279625483 67 0x177e550 WARN webkitwebsrc WebKitWebSourceGStreamer.cpp:1058:responseReceived:<source> error: R2: Received unexpected 200 HTTP status code for range request 0:00:03.280087141 67 0x177e550 ERROR webkitmediaplayer MediaPlayerPrivateGStreamer.cpp:1871:handleMessage: Error 9: R2: Received unexpected 200 HTTP status code for range request (url=https://blog.gtk.org/files/2020/09/Screencast-from-09-30-2020-05-39-53-PM3-convert-video-online.com_.webm?_=2) 0:00:03.297329531 67 0x177e550 INFO webkitmediaplayer MediaPlayerPrivateGStreamer.cpp:1037:notifyPlayerOfVideo:<media-player-3> Media has 1 video tracks 0:00:03.431302693 67 0x177e550 INFO webkitmediaplayer MediaPlayerPrivateGStreamer.cpp:1037:notifyPlayerOfVideo:<media-player-2> Media has 1 video tracks 0:00:03.592462522 67 0x177e550 INFO webkitmediaplayer MediaPlayerPrivateGStreamer.cpp:1278:isMuted:<media-player-3> Player is muted: false 0:00:03.731583687 67 0x177e550 INFO webkitmediaplayer MediaPlayerPrivateGStreamer.cpp:1278:isMuted:<media-player-2> Player is muted: false 0:00:03.982065953 67 0x177e550 WARN webkitwebsrc WebKitWebSourceGStreamer.cpp:1058:responseReceived:<source> error: R2: Received unexpected 200 HTTP status code for range request 0:00:03.982403814 67 0x177e550 ERROR webkitmediaplayer MediaPlayerPrivateGStreamer.cpp:1871:handleMessage: Error 9: R2: Received unexpected 200 HTTP status code for range request (url=https://blog.gtk.org/files/2020/09/toy-convert-video-online.com_.webm?_=1) 0:00:04.113870048 67 0x177e550 WARN webkitwebsrc WebKitWebSourceGStreamer.cpp:1058:responseReceived:<source> error: R2: Received unexpected 200 HTTP status code for range request 0:00:04.116096192 67 0x177e550 ERROR webkitmediaplayer MediaPlayerPrivateGStreamer.cpp:1871:handleMessage: Error 9: R2: Received unexpected 200 HTTP status code for range request (url=https://blog.gtk.org/files/2020/09/Screencast-from-09-30-2020-05-39-53-PM3-convert-video-online.com_.webm?_=2) https://bugs.webkit.org/show_bug.cgi?id=210284#c20
Is this still happening for you Michael? I can't reproduce this issue here on Ephy TP anymore. The playback stalls for buffering quite a bit, but I see no error in the logs, the video plays fine otherwise.
Yeah, seems to be mysteriously fixed. Can't complain when bugs fix themselves!
This has not been fixed by magic, this was a bug in the blog.gtk.org server who wasn't handling HTTP range-requests properly, which (for the most part) you need for media playback. In fact, it was in the logs: 0:00:04.116096192 67 0x177e550 ERROR webkitmediaplayer MediaPlayerPrivateGStreamer.cpp:1871:handleMessage: Error 9: R2: Received unexpected 200 HTTP status code for range request (url=https://blog.gtk.org/files/2020/09/Screencast-from-09-30-2020-05-39-53-PM3-convert-video-online.com_.webm?_=2) Range requests need to return 206 Partial Content. "200 OK" like in this log means the server didn't recognize the Range-Request, and therefore the data afterwards would come with the wrong offset, which is why WebKitMediaSrc is stopping with an error.