I also have the exact same problem with my Attitude SD goggles. Diagonal lines in video only when video out is used. Does not matter what I connect to, it is the same to my TV, old TV (fat size), DVR recorder and computer screen (Dell). The problem must lie within the goggles video splitter circuit or something which could also explain the the small change in brightness visible when connecting the video out cable. I might try to bypass the onboard electronics with a DIY video splitter, but first I'll try to install the TBS Dominator 5G8 rx which I have one coming my way soon. See if that helps...
Anyone except 'fatshark' that doesn't have this problem?