Set default player and add menu entries

I have downloaded a couple of addons (one for youtube and one for local webtv content). Since i have set mpc as my overall default player which now seems to have problem loading the web streams of the second addon, how can i set kodi internal player as a default but only for the addon content? The other question is how do i create subentries (my skin is rapier) so that i dont have to go tho the video->addon entry and find my addons there?