I found the post where your links didn't work (stumbled on it by accident, actually) and did a 'quote' to see where the problem is.
When pasting in a link to a video that you want to embed, you do not need to put tags around it. The forum software will auto-detect it.
The first link in your post was framed with FTP tags - this is a tag that prompts the viewing computer to try to download (which the link isn't properly configured for). Hence, 'server not found'.
The second link was framed with URL tags, which will properly send people to the video, but will not embed (a useful trick if the video contains minors, or if you simply don't want to embed it.)