尝试一下

private Uri uri;    //global variable

当用户从手机中选择视频时，

在 onActivityResult()内部设置uri

Inside onActivityResult() set uri when the user selects a video from phone

onActivityResult(int requestCode, int resultCode, Intent data)
uri = data.getData(); 

最终获得下载网址

final StorageReference ref = storageReference.child("firebaseFilePath");

    ref.putFile(uri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
        @Override
        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
            ref.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                @Override
                public void onSuccess(Uri uri) {
                    //now sUrl contains downloadURL
                    sUrl = uri.toString();

                }
            }).addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception exception) {
                    }
            });


        }
    });