Comparison of Existing Solutions

There are a lot of working solutions, but most of them work poorly so here is only a small subset of good ones.

1. video2midi

The best solution I've found. Works using Computer Vision analyze.

Has comfortable visual user interface to tweak things.

YouTube: Creating MIDI from hybrid Synthesia Video.

2. sheetesia

3. syn2midi

4. MIDI-Converter

5. pdf-omr-pmerge

7. synthesiavideo2midi

8. DeSynthesia

9. pianoroll_to_midi

10. JohnDoesStuff - Getting MIDI from Synthesia videos

No stars as it's even not in a separate repository, but it is actually not a bad project and it's better than a lot of projects above.

YouTube: Getting MIDI from Synthesia videos.