Well, that is something I read in the past week or so and now I can't find it
It was a detailed explanation of why it happens - it is an FSX bug - and how to minimise the problem. I came across it more or less by accident, so it probably is not in my usual haunts. I will keep looking.
I did find this in the Avsim forums:
" No, I do not think that he is referring to the beam. It's the actual "light glows" that I think he is talking about, and that's because I have the same issue. If I switch to a tower view (for example) to watch a quick replay of one of my planes landing, the lights are offset to one side of the plane. As the plane approaches, the lights slowly move towards the position that they are supposed to be in (ie. on the plane itself).
And that is a standard FSX issue.. as you move your point of view, the landing lights move on the plane. Unfortunately..Some vendors have implemented non-standard lighting that eliminates this behavior."