Sometimes there’ll be a required interview, which often has to be done by Skype. There are some cases in which the interview is really structured and formal, and you have to do it in-person. Sciences Po is a good example of that. Toulouse Business School uses the interview — it’s a recorded interview, but it’s sort of an entrance exam at the same time where they give you specific questions that you need to answer in a recorded interview.
But one of the main reasons for a Skype interview is to make sure that the English language proficiency matches the scores that they’re seeing. Those from the US should have no problems here!
Either way, it’s generally just a discussion of your motivation letter, but you don’t want to just regurgitate your motivation letter. So take your motivation letter and next to each point, note a few other examples that you didn’t include in the letter to make it a more interesting conversation and one that you’re then prepared for.