The word "them" is very frequent and usually understood to be the object of the sentence. So in common/informal speech it is very common to pronounce it as "em" or "um" or even just the "m" sound after a word. It can also happen for "her" and "him" being pronounced more like "er" and "im". These work in all accents and even in semi formal situations. However, if you are trying to speak properly and clearly, you should try to use the whole word. Side note: Sometimes "er" (short for 'her') is used in place of "it" but that is only in specific accents and situations. Eg. "Get 'er done." or "Git'r done." means "Get it finished." Other examples of shortened "them": Bring 'em to me. Can you talk to'em? (or "to 'er", "to 'im") Go get'm! Do you like'm? (could be 'him' or 'them') It doesn't always sound right, though, so be careful. This bag is for them. (normal) This bag is for 'em. (weird) Please carry that bag for 'em. (sounds okay but only if you were already talking about or looking at the people) I think 'em is probably weird sounding if the "them" word is emphasized or stressed but very natural when it is not. In "This bag is for them." the emphasis is about who the bag is for. Your friend asks who the bag is for and you say it's "for them" so you would say "them" with a bit of tension/stress and not shorten it. In "Carry that bag for them." the sentence is about what you are asking the person to do (to carry) but _who_ you are carrying it for is already understood. However, if you were trying to tell the person who they were carrying the bag for and you are pointing at the people saying "Carry the bag for them (for those people over there)", then "them" is stressed and not shortened to 'em. Sorry if that's a bit confusing. It's not a rule and you wouldn't usually write it that way, except for a comic book maybe. However, when speaking quickly and casually, it's just a way that people get a bit lazy.

Them in informal, colloquial speech, or just slang, is often pronounced 'em, 'm and so on. This person was speaking in that manner, which is why you heard lik-em :)

It's just an accent, and how fast they speak. The word will affect the way how they pronounce and if you're not good at the English language it's normal to feel confused. That's ok, you can learn it.

Yeah, more often than not that will be true. But that is informal speech. It’s not an accent thing, it’s a “connected speech thing”.

You know how I like them. Ya know how I like'em, straight up... It could be accent, or just contracting/shortening the words. I hear no audio of this film.