I would like to upload a video to a topic that I started about another issue on this forum but I keep getting this error message. I have tried .wmv and .mp4 with the same result.

Videos will need to be uploaded to a sharing site like google or dropbox.

I link to GIFs at dropbox for most of my screen captures.

Thanks tylerdurden. Do you know why it works that way. I'm looking for another option, because I don't use either of those services.

Inkscapeforum.com is like many community participation sites that restrict direct uploading of certain filetypes. It is common to restrict filetypes that use larger amounts of storage and bandwidth.

Until more resources are available, this is the way it is.

It is not a hardship for community members to open accounts at free sharing sites, and by doing so, it can serve as a contributions to the Inkscape community and developers. (Sharing the load, so to speak.)

These online sharing sites are not converting or compressing anything to my knowledge. So I should be able to convert the video to which ever file extension is supported by the software used to render media in this forum. I created a Dropbox and I'm having the same issue. It seems like there is something else causing this error message.

So far the file extensions I've tried are: .mp4, .AVI, and WMV

You can post a link to the media, if it doesn't embed in the message.

Example:
https://www.dropbox.com/s/0qyv50tczcnsu ... 0.mp4?dl=0

Dismiss the invitation to sign-up, at the bottom of the popup. ("no thanks...")

I was wondering if anyone has solved this issue without having to create an account with a third party. I'm trying to upload another screen recording for yet another question I have involving Inkscape but still get the same error message.

You can open an account on the new official forum and upload* many images/videos there.
https://inkscape.org/forums/

* new members will need to meet a minimum number of posts before being allowed to post images. Join up and present yourself, and after a couple of posts you can upload your media.

Better link to videos, there's a limit to how many files one can upload, and video files are usually rather large.