Clitics is just a fancy name (from linguistics) that DL sees fit to use for unstressed object pronouns - direct (DO) and indirect (IO). In English DO and IO pronouns are the same:
"She loves him " - him = DO
"She gave him a kiss" - him = to him = IO
In Romance languages DO and IO tend to be the same for 1st and 2nd persons - me, te, nos etc, but differ in 3rd person, for example o, a (DO), lhe (IO).
Romance languages also have a third form of pronoun known as tonic pronouns, used after prepositions and for emphasis - (para) mim, ti, ele, ela, nós, vóces, eles,elas. Note that in 3rd person they are the same as subject forms.
Incidentally, no standard Romance language courses for foreign learners that I have come across use the term clitic. Is it just DL being a bit pretentious, I wonder.
To find out more just google "object pronouns in Portuguese". This site gives a fairly detailed account for English speakers:
I need to listen to the male reader speaking slowly to confirm my answer. He tends to speak as if he were speaking to his friends on the street in Sao Paolo. Being foreigners learning a language he should be speaking more clearly. ...que eu as amo sounds like que eu os amo. Slowly spoken you can hear the difference but spoken rapidly it is impossible to differentiate.
I'm curious... I also thought that this could be translated to "You know I love you [voces]", but wouldn't:
"You know I love you [voces]" ---> "Voces sabem que eu lhas amo"
Or is "lhas" not even a word? I figure "lhe"= "to him/her/you", "lhes"="to them", then perhaps there's a "lhas/lhos"?
Yes, there is, but only if you have lhe+os or lhe+as, there is also a lho and lha contraction for lhe+o and lhe+a, I think it´s like "Você da lhes os livros"- "Sim, eu lhos dou." But to discuss the "You know I love you!"- question: It´s not that unlikely that you speak to a group of women, so why are they saying that it´s wrong?