can't add allowedContent feature from new plugin.js for html insertion in new button code

Hi,

I'm using WYSiWYG 1.5.6_0 [B551+23.01.2015], CKEditor 4.4.5 [revision 25cdcad] on 1.24.1 MW

and I had to create a new button for the EmbedVideo extension.

This extension is based on a specific tag <embedvideo service=...>http://...</embedvideo>
wich I'm trying to add via the button and a simple prompt for url.

I added my button successfully, prompt works but adds only the url pasted to the existing content.

I looked around for tips, but what ever I tried, could not avoid the <embedvideo...> tag to be stripped.

I thought that adding the allowedContent: 'embedvideo[!service]' line in editor.addCommand of my plugin.js would help but niet...

Anybody knows if this allowedContent or extraAllowedContent features still work ?

Thanks for your help/advices...

Here below my plugin.js for the button

CKEDITOR.plugins.add( 'video', {
    
    init: function( editor ) {
        //Plugin logic goes here.
		editor.addCommand( 'insertVideo', {
			
			exec: function( editor ) {
			    var services = ["bing","msn","dailymotion","kickstarter","metacafe","youtube","vimeo"];
				var videoUrl = prompt('Collez ici l\'URL de la video :');
				for	(servi = 0; servi < services.length; servi++) {
					if (videoUrl.indexOf(services[servi]) > -1) videoService = services[servi];
				}
				
				if (!videoService)
				{
					alert('Video Service not allowed : ' + videoURL);
				}
				editor.insertHtml( '<embedvideo service="'+ videoService +'">'+ videoUrl +'</embedvideo>' );
				},
			allowedContent: 'embedvideo[!service]',
		});

		editor.ui.addButton('Video',
                {
                    label: 'Insert Video',
                    command: 'insertVideo',
                    icon: this.path + 'images/video.png'
        });
    }
});