Okay so I'm starting off with the one you're instantly drawn to like I was and that's the Back to the Future/X-Men: Days of Future Past mash-up... it sucks. It literally just the trailer with Back to the Future II dialogue put over it and the background music dominates the audio. It's a bad video, but the idea was there. https://www.youtube.com/watch?v=wi26FeT88hI
The second one is a recut of the first teaser trailer and it's called Too Many Mutants... it captured my thoughts on this film and actually made me laugh so hopefully you enjoy it too!