Not all link formats work. Does just a normal youtube video with?watch= work?
Also did you enable youtube and other video sites under settings.
Under AdminCP -> Configuration -> Simple Audio Video Embedder should be near bottom on the left handside
The post? Or settings page?
What url are you trying to post will test on my side.
Hmm youtube worked let see about imgur here.
the imgur worked and the youtube just gives a single .
Odd let me check the imgur code . What about a separate post one with youtube then another post with imgur.