During an experiment deleting files from a flash drive, the results were as follows:
1. It did not recover or detect MKV files for recovery (the file size was 4.43 GB).
2. It recovered all graphic files, but it was impossible to view them after recovery.
3. It successfully recovered multi-page PDF and TXT files, as well as small MP4 video files. I didn't experiment with music files. Overall, I didn't like it; it's weak. I only use programs like these for experimentation, as I don't really need them. Disk Drill recovered data the fastest http://www.handyrecovery.ru/, and that's the one I use. I think this might be useful to someone.