formats playback
 

A NTSC made DVD can it be played in France (SECAM)? or PAL-N, PAL-M countries?

That totally depends. A lot of eurepean equipment can handle
NTSC DVD's or can convert them on the fly. But not everything.
I don't have any numbers for you. If you want to be 100% safe
make a PAL DVD. To the best of my knowledge there is no such
thing as a SECAM DVD. The SECAM countries all use PAL DVD's.
They might use a slightly different DVD player, but as long as your
DVD's are PAL compliant they should work.

Whether or not the risk of sending an NTSC DVD is worth it
depends on what you are sending, to whom and why.

Played and seen, meaning:

Most of the DVD players in Europe can play NTSC and PAL DVDs. A lot of TV sets cannot play both systems, that's the problem.