Why Do My Videos Not Play After Google Takeout?
Old formats stop playing on modern devices. Takeout hands them back exactly as they were uploaded.
Because Takeout returns your videos exactly as they were uploaded, and some of them are old.
Google Photos played them for you in the browser by converting on the fly. Your computer has to open the actual file, and formats like AVI, WMV and 3GP from an old camcorder or a 2009 phone are no longer supported by much. The file is fine; nothing is corrupted. Modern players simply dropped support.
They also come back with the wrong date, for the same reason your photos do.
The app fixes both. Videos get their real dates written back like everything else, and there is an optional conversion that rebuilds only the old formats so they play again. Files that already work are left completely alone, with no quality loss. The first 500 photos are free.