Could not reproduce on Win10/Ubuntu20.4/Mac10.13 using builds Beta 103.0b8 (20220712185923) and Nightly 104.0a1(20220712215641) using information from description. So I found and online site to download .mp2 (https://filesamples.com/formats/mp2#google_vignette) and download was performed on Win10/Ubuntu20.4/Mac10.13 using builds Beta 103.0b8 (20220712185923) and Nightly 104.0a1(20220712215641) without any issues. Downloaded file name contained the '.mp2' and file played.
Bug 1772988 Comment 4 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
removed comment.