animation won't play on DND

[SaladGoat]

Previously I was able to drag and drop animated gifs, and video files (mp4, webm, etc) into Firefox and watch them.
Since updating to 80.0.1 (not sure what version I was on prior, but would have been only one or two sub-versions lower) when dragging and dropping such files, I end up with the "code" - just pages and pages of useless gibberish like so:
GIF89a������|��t���������������������,*$��l��|��|���"$"�¼$������dJ4������������tzd|�t��
(That's just a small sampling, of course.)
Videos and gifs still load and play as expected when presented in web pages. Even when the video itself is loaded alone from a website (ie right-click>View Video), it works. But to view on their own, from a local folder, nothing.
What happened? More importantly, how can I restore the functionality? Is there something in Settings or about:config or somewhere else that I need to twiddle? Or is it a bug that Firefox will fix shortly?
Thanks!

[dickvl]

That is a GIF header.

Did you make sure that the image files have the correct file extension ?

Does it make a difference if you use "File -> Open File" to load the image ?

You can check the image.animation_mode (normal) and ui.prefersReducedMotion (0) prefs on the <about:config page.
ui.prefersReducedMotion = 1 will block animations; ui.prefersReducedMotion = 0 will allow animations

[SaladGoat]

Yes, they are all valid files with proper extensions. And yes, it's the same problem if using File -> Open.

But here's the weird part: it's working now!

It was behaving like this yesterday. I rebooted the computer last night, and it continued to do the same thing today, which is why I asked for help.

But shortly after posting this, Firefox was doing weird things, so I shut it down (only the browser, not the whole computer). Five minutes later, I started Firefox again, did a few other things, then thought I'd give it another shot, and now suddenly it can open gifs and videos.

I did nothing else. I don't know what happened. I am hoping it doesn't happen again, but if it does, I will look into the tips you provided.

Thank you!

[therube]

See if this (NoScript) Firefox can't open local image anymore relates?

[SaladGoat]

NoScript says it's at 11.0.43 and everything is working now. Maybe it was at a previous - glitchy - version and updated itself on the last Firefox restart?
Thanks for the input - I will try to remember that if it happens again.