The best way I've found to post anything on a forum is through a third party hosting site. For video, I post to my YouTube channel, then either link or embed the video in a post. For posting pictures, I use imgbb.com. Upload pics to there, and then using the provided bb code, link or embed the image into a post. It all sounds like a hassle, but it saved Knifedogs a lot of server space if you do it that way.
There is only so much space on this, or any forums' server(s)..... and most will only allow for a given amount of disc space usage for uploading pics or videos. Uploading a picture often takes several Mb or space, videos these days are often Gb of space..... The more space required for the forums, the more it costs Tracy and company..... and since all of this is free, let's take care of Tracy as much as we can!