Insanely accurate
I just downloaded the free version and used the proof-of-concept demo on the website. It uses 3 test videos: one is perfectly in-sync, one has 112ms later sound and one has 112ms earlier sound. Measuring the 112ms-earlier-video resulted in „106ms early“ (on my iPhone 13 mini, 16.5.1) and measuring the 112ms-later-video resulted in „112ms late“. Pretty impressive!