I find it petty, odd and downright rude to look down on other people because they weren't taught exactly the same sounds as you. It's reasonable to prefer to use one form of words over another yourself but I think its unreasonable to assume that everyone born in a certain geographical area is saying it 'wrong' just because they have picked up some of the culture of another geographical area (or in the case of some of the examples here, they have a more local culture that you are unaware of).
Language evolves. People also use language differently in different contexts. If I didn't mind sounding more posh/formal I could've said "one" rather than "you" in the above paragraph.
I'm from Scotland, have lived in Devon and I am currently living in Scotland again. I use the words pictures, cinema, movies, film (and possibly filum!) - sometimes interchangeably, sometimes I use different ones in different contexts. Film denotes in my mind a more serious, quality picture than a movie, which I think of more as a fun, popcorn worthy blockbuster, possibly American. I don't think there is anything wrong with having both words.
One phrase I found unusual in Devon was "Where's [something] to?" rather than simply "Where's [something]?" but after living there for a couple of years, I find I sometimes use it myself.
My son is at the stage of learning to talk and amongst a few words of English he does a lot of babble in the rhythm and tone of language. It is very cute and a great reminder that language is just a matter of finding sounds that have common meaning with the people you are trying to communicate with. English (with the odd Scots word or phrase thrown in) is one pool of sounds he's learning to decode - BSL is another, the associated noises is another. Important words like train ( ) he knows the word Train, the BSL sign for train and the chuff chuff noise. With other words he might just know the sound (e.g. an animal noise), the sign or the word. I'm sure as he grows up he'll learn his generation's own slang amongst my Scottish English and DH's West Country English and that's just as it should be. Of course he'll be taught the difference between formal English for essays/job applications/work stuff versus informal English for use on internet forum boards, dialogue in creative writing or speaking to family and friends.
But then, I've taught my son how to high five so what do I know . It's fun and I also find that it and blowing kisses is a good none physical way for him to show friendliness to people he doesn't want to kiss or hug. I'll add hand shaking to the toddler curriculum if that makes people feel he's learning something 'British'. As for not high five-ing adults, I think I might have occasionally, but we do all sorts of things with babies and toddlers that we'd never go up to another adult and do, tickling, blowing raspberries on them etc.
I like America. I think it's a snobbish to treat Americanisms as if they are inferior when they are perfectly good words, particularly for describing things that are American in origin, like the latest Hollywood blockbuster.
Feel free to pick at my grammar if you don't have anything better to do.