Learn English – How to use of the word “seem” in negative form

Your usage of "not" and "don't" is correct, but there are other things in the sentence that are incorrect. For example:

Some people think taking part in those classes could be useful and some others don't.

This is correct, but the more idiomatic way to say this is:

Some people think taking part in those classes could be useful and others don't.

I like watching movie, whereas my sister doesn't.

In this sentence, "movie" should be pluralized to "movies"

They are good at selling but another group not.

This sentence is missing a word. The word "not" should be used with an auxillary verb. (Verbs like "be", "would", "did"...)

Here, you should add "is" before the not.

They are good at selling but another group is not.

or even

They are good at selling but another group isn't.

1. I mistook the correct usage "I satisfy your requirements" with "I satisfy with your requirements".
2. "I satisfy with your requirements", by itself, is a wrong use of "I'm satisfied with your requirements". I'm confused the former with the latter.
3. "I'm satisfied with your requirements", by itself, is weird in the meaning because we're only satisfied with the service or the manner that others giving us, although the sentence is grammatically correct.

So you either say "I satisfy your requirements" or "I'm satisfied with your service".

^{Related: Can one meet criteria, or satisfy requirements?}