Add video player widget /example/

[FelixZY]

Is your feature request related to a problem? Please describe.

I want to play video.

Describe the solution you'd like

I would like an example of how to create a video player to be added to the examples directory.

Describe alternatives you've considered

• A built-in video player widget
  • Probably a good idea and could serve as an example as well. Might not provide enough customization options for advanced use cases though.
• https://github.com/n00kii/egui-video
  • Not really happy with

    need to compile in release or opt-level=3 otherwise limited playback performance

  • I Would prefer a first-party widget or example

Additional context

I'm looking into creating such an example widget, using gstreamer as the backend. I'm not yet sure I will succeed.

For anyone else starting out, a custom AppSink seems like a good way to go. There is also an example using opengl which might be useful with egui_glow.