Fair use can be such a grey area, the line is drawn by judges, and at the end of the day judges are people whom contain their own bias. Lets assume for a moment that Lucas decided to sue the creators of these two videos for copyright infringement, would he have a case? In the first video “Star Wars Fan Film: The Essence of the Force”, one could argue that this is a clear case of fair use as this is a parody, as they are clearly spoofing particularly at the end of video. However, Lucas could argue that they stole scenes and ideas from his movie, and they did not add anything new to his original idea, and therefore it would not be transformative and would not follow under fair use. One would hope the presiding judge in this fictional case would side with the defendants.
Now lets look at the next video, “Star Wars Saga (The Best Trance Remix Montage)” A montage by definition is a set of scenes usually set to music. On YouTube many users upload scenes from movies set to music, sometimes their own sometimes someone else’s. Lets presume this montage has original music, it still sampling all the scenes from Star Wars. Lucas could then argue that since 100% of the scenes are from his movie, this a clear violation of copyright infringement. The creator of the video could argue, that since he is not profiting from this video he is not harming the original, and is in fact paying homage to Lucas.