With Attached example, looks like seekableChanged is not firing when run with WebAssembly. Same example when run on desktop (linux/mac) it seems to be working.

Following logs are coming from Desktop and Webassembly:

Linux:

qml: -PLAY-
qml: STATUS:
error: 0 errorString: mediaStatus: 1 playbackState: 0 duration: 0 position: 0 hasAudio: false hasVideo: false videoTracks: [] seekable: false
qml: duration changed: 10000
qml: video tracks: [QMediaMetaData()]
qml: seekable changed: true
qml: has video: true
qml: media status: 2
qml: media status: 4
[h264 @ 0x5f0149046f00] No support for codec h264 profile 100.
[h264 @ 0x5f0149046f00] Failed setup for format vaapi: hwaccel initialisation returned error.
qml: media status: 5
qml: position changed: 100 seekable: true duration: 10000

WebAssembly:

appwasm-video.js:1342 qml: -PLAY-
appwasm-video.js:1342 qml: STATUS:
appwasm-video.js:1342 error: 0 errorString: mediaStatus: 0 playbackState: 0 duration: 0 position: 0 hasAudio: false hasVideo: true videoTracks: [] seekable: false
[Violation] 'pointerup' handler took 169ms
appwasm-video.js:1342 qml: media status: 1
appwasm-video.js:1342 qml: duration changed: 10000
appwasm-video.js:1342 qml: media status: 5
appwasm-video.js:1342 qml: media status: 2
appwasm-video.js:1342 qml: position changed: 223 seekable: true duration: 10000