what's the difference between 'You shouldn't do something' and 'You shouldn't be doing something'?
does the latter one imply that you have already started doing something?

e.g.
1. It's midnight now, you shouldn't watch TV (you are not watching tv now)
2. It's midnight now, you shouldn't be watching TV (you are now watching tv)

is my understanding correct?

Question

what's the difference between 'You shouldn't do something' and 'You shouldn't be doing something'?
does the latter one imply that you have already started doing something?

e.g.
1. It's midnight now, you shouldn't watch TV (you are not watching tv now)
2. It's midnight now, you shouldn't be watching TV (you are now watching tv)

is my understanding correct?

Answer

The second one is a general statement. The first one is specific to that moment, that time. It may or may not be true for other nights.

Answer

The first is a simple statement of fact. It's late; you shouldn't watch TV. You can say this whether the person is watching TV or not.

The second one you would only say if someone is actually doing the thing they shouldn't be doing, so your understanding is correct.

Good job :)