Hi!

The sking I used had flash logos. The main one showed the time, and there was a throbber thing for loading videos.
What (animated) formats can I use? Can I convert the swf-s?
I'm hoping it's more than gif because it's a really outdated crappy format.

Okay, so I did a bit of testing.

Not even animated gif works! Only the first frame is shown. (APNG also doesn't work.)

This doesn't make much sense. Potplayer can decode and show these animations (even APNG) when I open them for playback. So it surely has the capability of doing so. But not even supporting ancient, widespread gif is a major disappointment.