On some of the Columbia's Laserdiscs (french ones), notably Last Action Hero (1993) [LD 19669] and In the Line of Fire (1993) [LD 19668], which are, for now, the only two that I know of with this marking.

There is, on the right bottom of the back cover, an inscription saying "Pas mal à trois" which literally could be translated to "not bad at 3" or "on 3".
The thing is, in french, this expression ("pas mal à "insert number") is usually referring to something that is quite good once you get with other people. Example : "Ce jeu n'est pas mal à trois" = "This game is not bad with 3 people (you + 2 other player)"

So the 1 million dollar question is, why is this written on the back on those movie covers ?
Is it some kind of movie critic, like "This film is not bad once you get 2 other people watching it with you" ?
Or is it just some silly private joke that might have been put here by someone like the cover designing staff for example ?

I found a few more:

Lawrence of Arabia (1962) [LD 12058]
Léon (1994) [LD 21219]
Philadelphia (1993) [LD 19882]

Inside-jock signature of the production/design team for the French release?

Julien

http://archivesbidard.free.fr/auteurs/VERNE_Jules.htm lists a videotape that's "VHS / SECAM - Edité par PAS MAL A TROIS".

So, searching in my Columbia's LDs, I found two other with the same inscription:

-Striking Distance (Piège en eaux troubles (1993) [LD 18642])

-Look Who's Talking Now (Allô Maman, c'est Noël (1993) [LD 20763])
This one have the inscription being written from top to bottom (all the others have it written from bottom to top)

Thanks to Julien, I know that on Philadelphia (Philadelphia (1993) [LD 19882]) Three is not written in letters, but "3"

Searching for things linking them, I found out that all of them have been released on Laserdisc between 1994 and 1995, so the one behind all of this was probably only working for Columbia home video for around a year or so as a designer.