Re: overlay feature missing.
Note that in twinview hardware overlay is not possible as there's only one overlay and that's complicated. Nowadays there's some extra overlay backend next to plain blitting so there's some Xv but perhaps just software.
To get fullscreen on the tv you need to use a mediaplayer that supports Xinerama. Both mplayer and xine support this but there is some option you need to activate. Using xinerama the player "knows" what the visible resolution on lets say the TV is.