I have tried PlayVideo from openfl-samples and it works fine when using mp4-video. But webm-video doesn’t play, and next runtime error occurs: Unhandled NetStatusEvent:. level=error, code=NetStream.Play.StreamNotFound.
Also i have tried haxelib https://github.com/soywiz/haxe-openfl-webm. But compile time error occurs: You cannot access the sys package while targeting flash(js) (for sys.io.File)
The webm-library that you linked hasn’t be updated for years and didn’t work when I tried it some years ago. It’s wasn’t ment to be used for html5/flash.
As for webm support on flash there’s none for bare bones flash. Someone did an alchemy port of a lib that supports webm but that one was too slow for anything. If you develop for Air there’s an ANE:
As for HTML5 you should keep in mind that IE doesn’t support webm natively. Users don’t enjoy being asked to install a plugin to playback a video, so you should have a MP4 ready for IE users.
Usually you’d convert your videos to mp4 using ffmpeg or similar since the results will run pretty much everywhere