Does anyone remember a scifi movie that starts with two sibling (a boy and a girl) each receiving a pair of rollerblades as a present. The sister has an accident which results in her having to go to hospital. A neighbour reveals to the brother that his sister is in danger and that the video games she has been giving him is training for just these sort of events. The sister is revealed to be some alien (princess?) in hiding with a adopted human family (unknown to them).

Try The Distant Home (http://www.imdb.com/title/tt0284054/)

Thanks a million, that was it!