"You don't have permission to open this file."

[MaestroLM]

My apologies if this seems a "but that's what it says" issue; I've searched my problem here and found nothing in a common thread - and I'm running the most updated build of Win11(home,) so here goes:

"You don't have permission to open this file."

Here's the problem: this particular .mp4 DOES open in four different player programs I've tested. No problems; no apparent age restriction - and I downloaded it while signed into my YouTube account. I can even import the .srt file into those player programs - and perfect results.

But I get that quoted message above if I try to upload it to Handbrake.

I've followed all the troubleshooting recommendations: uninstalled/reinstalled Handbrake and windowsdesktop-runtime-8.0.20-win-x64; restarted my computer but still: NO GO.

Why should an otherwise innocuous .mp4 NOT open in Handbrake when it opens in every other program I've tried? I do have the full activity log - but didn't want this interminable post to get even longer. But WILL show it if anyone thinks it'll help with a resolution...