Yeah. You could replace "ass" for "neck"; that would make it sound less vulgar, or you could just say "It's a pain". I think your usage is wrong, though. This phrase is more appropriate for persons, not things. You would use it when describing an annoying or bothersome person. For example, "My little brother is a pain in the neck".

The expression doesn't fit here. say, "it doesn't feel like work to me if it's a Disney movie."

It depends who you are writing for.If it's for a teacher at University then don't use "ass" ,write "neck" :-)

The correct sentence would be: 'I like Disney movies. Although I need to repeatedly watch the same one to understand what characters are saying, it's not a pain in the ass FOR me if it's Disney movies.' 'Pain in the ass' is an expression and is always used like this, therefore you can't replace 'ass' with another part of the body such as 'neck'. In general this is a bit extreme to say and implies you are actually angry or really annoyed with something. Also it's a bit rude, so you might want to avoid it depending on the people you are with. If you want to be safe, you can just say 'it wouldn't be a pain' and this is not at all rude! Hope this helps.