This IS the correct category.
The Discourse forum engine has OneBox built-in. (But recently there has been some issues with the OneBox plugin and 3D Warehouse model links.)
Try posting the URL to the video file directly on a line by itself, with no spaces in front of the URL, and see if the OneBox plugin can render it correctly. [The space prefix is a "nifty" way of suppressing the OneBox'ing.]
(Do not attempt the post an HTML frame url. It will be stripped out.)