Piano2MIDI How to record video of MIDI visualizer and real piano player integrated into one?

Not an expert, but definitely looks like a simple overlay of a synthesia video on top of a recording of him playing the song on a keyboard. So, say you want to record this in one go, you need to:

1. load the midi file of the song you want to play in synthesia
2. use screen recording software to record the computer screen while it's playing the song in synthesia
3. at the same time play along with a midi keyboard and record this with a topview on your phone
4. in video editing software, crop the keyboard video to show the keys and your hands only. (convert to black & white, if you REALLY want the same effect)
5. in video editing software, overlay the synthesia video on top of the (cropped) keyboard video and use some kind of blend mode e.g. "multiply" this will give you the effect of the colours radiating on your hands and the keys

So no, there's no need to place a large tv over the keyboard. it definitely won't look the same.