New filelfield browser widget is massively confusing the user

I'm confused why there's the additional step as well. If the intent was to make it work more like the core File or Image fields, I don't understand. They don't have the concept of two submissions.

This functions the same as file.module's managed_file form element: you choose a file (local machine/media browser) and then upload/attach the file. This allows users to select a different file before uploading/attaching it in case they chose the wrong one by mistake.

On the code side "attaching" the file allows all of the validation, access, previews, etc to happen on the backend instead of through JS which makes development a lot easier, makes testing possible and allows the field widget to be used with JS disabled.

As with the managed_file form element, the file will still be attached if the user presses the submit button without first attaching the file. I'd suggest filing a bug report with steps to duplicate the issue as there is currently a test for this in media.test:

        $test_file = $this->getTestFile('text');
        $test_file->uid = $this->admin_user->uid;
        $test_file = file_save($test_file);
        $path = 'media/test/' . $tree . '/' . $extended;
        $input_base_name = $tree ? 'nested_media' : 'media';

        // Submit without a file.
        $this->drupalPost($path, array(), t('Save'));
        $this->assertRaw(t('The file id is %fid.', array('%fid' => 0)), 'Submitted without a file.');

        // Submit a new file, without using the Attach button.
        $edit = array('media[' . $input_base_name . ']' => $test_file->fid);
        $this->drupalPost($path, $edit, t('Save'));
        $this->assertRaw(t('The file id is %fid.', array('%fid' => $test_file->fid)), 'Submit handler has correct file info.');

That said, I initially included the JS required to automatically attach the file once it has been selected in the media browser but I removed it in order to be consistent with the managed_file element. The attached patch restores the automatic attach if that's the consensus. :)

It would also be simple enough to make this configurable per field instance if that was desired.

I'm also missing the possibility to edit a file entity on a node form. I made a new issue, but I belive it is related to this as it happened after upgrading: #2217061: Edit options on imagefield missing

If I understand correctly, the requirement for the user to be able to choose a different file is to cover the case when they click on the wrong thing in their browser's file chooser. If that's the case, they can already choose a different file before they upload, they just need to do it in the media browser popup instead of on the node edit page. I am in favor of the auto attaching. It seems unnecessary for the user to have to confirm their file in both the media browser and the node edit form.

Patch is being used on a project with multiple testers/developers and has not presented any problems yet and has provided the desired functionality

Confirming that patch #2 is working.

Confirming patch works as advertised. RTBC

Committed to http://drupalcode.org/project/media.git/commit/fe09f09.