I'm not so keen on the 2nd of 3 FX this guy picks out, but this is a nice video for a quickfire intro to masking, which is a really powerful tool.
I used it a lot in the Xmas video, a 10 hour total edit, so it's a very achievable effect. Indeed, I'd never used it myself until I googled on the bus back from Avignon in September, trying to figure out how to layer inside the curved archways of the ancient viaduct there. I also used it in the Not Ones final video to layer on the Scoble Scale clips.
What I also like about this video is the guy's thought process - he knows a hell of a lot more than me about FCPX but we both look at videos and ponder how to reverse engineer some of the FX we see: try to work out how we might achieve this in FCPX, regardless of what suite was used for that video. I find that a great way to strengthen my familiarity with FCPX and editing techniques more generally. In this video he noticed that the 2nd effect (all 3 are taken from an actual music video) definitely comes from FCPX.
Have a gander for yourself...
https://youtu.be/vZUvzh42qH0