Here's the program I use to make the beat markers in my videos.
I've been working on it for over a year now, and I feel like it's finally in a state where it's easy and enjoyable to use.
Currently, it isn't self-contained and has to be ran using the Godot editor.
For information about updates and discussions about features, check out the bx_development channel in the Dildo Hero Discord server:
https://discord.gg/t2CKPvenet
Feel free to message me if you have any questions about using it <3