Could be two separate problems (not unusual with seaeyes)
fuzzy video – check out the video driver settings (or shielding following a reterm)- maybe ignore the settings in the manuals and go for trial and error.
losing overlay – if the vehicle is working full pelt, the video overlay is usually the first thing to brown out – check out your power supply and or make sure you are "easy-easy" on the controls.
One more thing to look for – when you are flying, if the ammeter is fluctuating then it is possibly a sign of a future problem in the Vpsu (showstopper).
Good luck,hope this helps, pm me if you need any other pointers. 😉 😉