I've always found the top-down angle of the piano keyboard to be a very clean look. It shows exactly where the fingers are landing, and provides a good perspective of how the hand is moving across the keys.
I recently put out a recording of a piano cover on "A Mother's Prayer" by the Gettys using this angle. Some people asked how I achieved this view of my keyboard, so I'm writing this to share the setup that I used. Links will be provided for all of my gear, should you want to try this out for your own recordings!
My camera rig consists of the following: an iPhone SE, a boom mic stand, a screw adapter, and then a phone tripod adapter. A lightweight camera works best, as it minimizes the amount of strain that is placed onto the stand. Place the boom mic stand right behind the keyboard, and then fiddle with adjustments until the phone is positioned above the center of the piano, at a height where you can still see the screen. Head into the iPhone's stock camera app, and there should be a cross hair that shows up in the center that helps you align the phone so that it's parallel to the floor. You can also turn on the grid lines in the settings to help with framing (Settings > Camera > Grid).
Switch the camera mode over to video, and if this range of the keyboard is all you want to be visible, then you're all set to start recording! However, if you want to capture a fuller range of the keys, you'll need to raise the height.
Since you won't be able to see my phone screen when it's up there with the raised boom stand, you need some way of monitoring the iPhone's screen feed for framing the video. There are various software solutions, but I made use of AirServer, which allows my MacBook to be a screen mirroring receiver. Mirror the iPhone's screen to your computer, and then position your setup so that your computer screen is in view as you adjust the height of the boom stand.
Since you already made sure that the tilt of the phone is correct, all you need to do now is raise the height of the stand and adjust rotation so that your frame is positioned and aligned to your liking. Once you have your shot, tighten the stand, double-check on alignment, and walk away. Nicely done, you're all set to capture a top-down video of your piano playing!
(Quick note: if you don't have a means of getting up to your phone to hit the record button, you can find some way of remotely starting the recording, or simply press the record button before raising the stand.)
I'm sure this isn't the only method to capture the piano at this angle, so if you have any other solutions, definitely let me know in the comments! I'm always looking for ways to speed up and improve my own workflow.
Full list of my gear: