Some of the effect bitmaps in the FSPort mediavp (most notably Avenger_Bitmap) seem to have faulty alpha channels. Instead of using pure additive blending like with normal effects, less intense areas of these bitmaps darken any bright things (nebulae, ships, skyboxes) behind them. I have fixed versions of a few of these bitmaps (removed the alpha channel, so they blend normally) and wonder if you would like to put them into the official FSPort mediavp.
(and also, in my opinion, the Avenger should use the old Maxim_Impact from 3.6.8 since it's a projectile weapon that probably fires explosive shells)