for you to watch

Which are correct:

  1. These films are for you to watch.

[color=darkred]2) I brought these films for you to watch.

[color=blue]3) These films are so that you can watch them.

[color=darkblue]4) These are so that you can watch them.

I don’t think ‘3’ and ‘4’ work in formal English. Maybe they can work in conversation if one is handing over the films and intends to say ‘I brought these films so that you can watch them’.
I am not sure.

As for ‘1’ and ‘2’, I think they are ambiguous.

ONE POSSIBLE MEANING: You can watch them these films if you want.
SECOND POSSIBLE MEANING: You have to watch these films.


Your observations are correct.