Thanks for your answer.
I don't really think it's a necessary feature, but I had to record a bit more and then delete some screenshots to get what I wanted.
What I mean is (at least while recording fullscreen), since I can't see for how long it has been recording, I have to know where to stop manually.
Not that it's that troublesome, but having a way to tell "I want to record for xx seconds" could help a bit, IMO.
Anyway, I tried combining 2 replays and it works just great! (I just have some artifacts after using matte difference).
Oh, almost forgot a little bug, although it doesn't seem to be related to LFS Record: I recorded the same camera animation 3 times (once without any car, and then with 2 different cars), and I noticed the trees had no leafs at all, except in one of the recordings... And as I just started LFS, my trees still have no leafs.