Most disc masterers (is that a word?) these days look for a nice clean scene transition. A black or stationary picture isn't the only requirement, since the sound will "blip" as well and would actually be more noticable to viewers than a paused picture.

I don't believe any current player - fourth generation included - completely remove the visible signs of layer changes. Some players are just better than others (a few players, on certain discs, can have REAL problems).

In Lost in Space, I forget the chapter, but it's when Will is talking to Dr. Smith (starts off with him holding the gun on Smith) and they decide to leave the ship. SOMEWHERE during that conversation is the layer change. Poorly placed for those using certain players, but I couldn't find the change anywhere.

...OK... I just read my own review of the disc. It's at 1:30.56 into the entire film.