Usage of Widgets in Plugin Groups

Hello

I'm new with elgg... is it possible to ad widgets in Plugins? Mean, it will be nice to add developed Widgets, like a mediaplayer, to the group page -> elgg/pg/groups/17/groupname/

I try'd
Made Widget in -> elgg\mod\groups\views\default\widgets\Mediaplayer

added line in  \elgg\mod\groups\start.php

add_widget_type('a_users_groups',elgg_echo('groups:widget:Mediaplayer'), elgg_echo('groups:widgets:Youtube Player'), 'groups');

But nothing.... ;-(
Is possible to do something like this, or no way?

 

thanks for a short statement
sorry my english