lightbox: Offer to open browser if video player doesn't support a video format

[chrisbobbe]

Sometimes the video player fails to initialize because the video format isn't supported:

The app relies on the platform's (iOS or Android) set of implementations for playing videos of various formats. Sometimes the platform doesn't support a video but the user's browser does because the browser brings its own implementation. For example, it fails in the app for me on iOS 18.1.1 but succeeds in Chrome on the same device. See discussion in beta feedback.

So, when a video is unsupported, it would be helpful to offer to open it in the browser.

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Implementation notes:

Here's the note from the library we use, video_player:

https://github.com/flutter/packages/tree/311b660c6/packages/video_player/video_player

Supported Formats

• On iOS and macOS, the backing player is AVPlayer.
  The supported formats vary depending on the version of iOS, AVURLAsset class
  has audiovisualTypes that you can query for supported av formats.
• On Android, the backing player is ExoPlayer,
  please refer here for list of supported formats.

[…]

The error I get on iOS is a PlatformException; here's what went by in the logs:

flutter: VideoPlayerController.networkUrl(https://chat.zulip.org/user_uploads/2/86/dBbfIDB3gWLscD3dQXnsBlXc/Screencast-from-2024-12-26-00-48-11.webm)
flutter: VideoPlayerController.initialize failed: PlatformException(VideoError, Failed to load video: Cannot Open: This media format is not supported.: The operation couldn’t be completed. (OSStatus error -12847.), null, null)

Looks like the structured "code" part is just a generic "VideoError", and the part that says it's specifically a format issue is this string:

Failed to load video: Cannot Open: This media format is not supported.: The operation couldn’t be completed. (OSStatus error -12847.)

Rather than parsing that, let's try just assuming a "VideoError"—or perhaps any error—is a good reason to offer to open the browser, and do so.

If the video is on-realm, needing authentication, we should use the "temp file URL" protocol; see api.tryGetFileTemporaryUrl in zulip-mobile.

[chrisbobbe]

zulip-mobile lacks an in-app video player and just always opens videos in the browser. This is usually a worse experience (the change of context could be annoying), but ends up being better in this uncommon case (where the platform doesn't support the video but the browser does).