No, this bug is not fixed, even not on the Beta server.
I reported this bug already on July 2019.
The approach of @drpeterramsis2007 is not really a solution or a trick, as you should always avoid that unnecessary permissions are required (in this case: READ_ / WRITE_EXTERNAL_STOARGE).
Therefore you should wait for a fix or use an extension.
If you still want to go this way, you have to use Taifun’s file extension (App Inventor Extensions: File | Pura Vida Apps), because the File component does not work when copying from the assets (I reported this bug also serveral times).
Check this APK: videoPlayer_test.apk (5.4 MB)
The video testVideo.mp4 is copied from the assets to
/storage/emulated/0/Download/testVideo.mp4
and is played from there.