MIDITrail

Hello,
I think it would be desirable for an app to have a recording function,
but these days the OS provides a convenient screen recording function.
Below is a workaround for that request.

----------------------------------------
Windows 10,11

You can use Xbox Game Bar.

(1) Click on MIDITrail window's title bar.
(2) Press [Win] + [G] key.
(3) Click the record button.

Note:
Since the menu bar will be recorded, it is recommended to hide the menu bar in advance.
You can hide menu bar of MIDITrail by click "View"->"Menu Bar" or press [F12] key.

Record a game clip on your PC with Xbox Game Bar
https://support.microsoft.com/en-us/windows/record-a-game-clip-on-your-pc-with-xbox-game-bar-2f477001-54d4-1276-9144-b0416a307f3c

----------------------------------------
macOS

You can use Quick Time Player.

(1) Open Quick Time Player app, and choose "File" -> "New Screen Recording".
(2) Set the location where you want to save your screen recording.
(3) Click Record button. To stop recording, click the Stop Recording button in the menu bar.

Record your screen in QuickTime Player on Mac
https://support.apple.com/guide/quicktime-player/record-your-screen-qtp97b08e666/10.5/mac/12.0

----------------------------------------
iOS (iPhone, iPad)

You can use Screen Recording button.

(1) Go to "Settings" -> "Control Center", then tap the Add button (+) next to Screen Recording.
(2) Open "Control Center" on your iPhone/iPad.
(3) Tap the Record button.

Record the screen on your iPhone, iPad, or iPod touch
https://support.apple.com/en-us/HT207935

----------------------------------------