gifv is a video, not an image, nb. Old board couldn't display them.
Interesting, but gifv isn't on the list of supported videos so I didn't even try it.
In the video link pop up: And any direct link to .wmv / .avi / .mpg / .mov / .mp4 / .ogv / .webm
And it's displaying in your post as both an image and a video. Weird architecture (check your post and view the BBCode).
I've noticed this forum's codebase does some things oddly compared to old phpbb... like changing anything about the font of a hyperlink has to be placed outside the hyperlink or it is ignored. Probably a shift in php code structure over the last 20 years... but I digress away from teh funney...