The phrase "tme dass123720m4v" appears to refer to a specific technical identifier
MP4Box Re-Muxing : The original file had a corrupt moov atom (the index table that tells players where to find video and audio tracks). By extracting streams and re-muxing with MP4Box, the fix restored seek functionality and timeline accuracy. xxxmmsubcom tme xxxmmsub1 dass123720m4v fixed
DRM Strip and Repair : M4V files frequently contain FairPlay DRM. A "fixed" version might remove only the DRM that causes playback errors on non-Apple devices, while preserving metadata and chapters. This is a contentious but common practice. The phrase "tme dass123720m4v" appears to refer to