Ok, i tried some variations.
Full Screen Video Options: I tried to set it up to show my video on tv. If i start the video all is fine, but if i start a game, the video switched to black and the game apears in fullscreen on my tv and tft.
Desktop Extension: I have maximized my DVB-S program and moved it on my Desktop Extension. Works, but if i start a game, the game minimized and wont come up again.
(Fullscreen video off)
I tried with switching primary and secondary Video Adapter, but nothing works.
Second Problem: If i restart windows, my signal format i set up before is back to default.
I have connected my TV over S-Video.