This has been going for quite some time. I used to write it off to my using a $98 WallyWorld windows tablet, coupled with slow cellular internet (shrugs)
but now that I have pretty fast WiFi and a Lamborghini gaming laptop, I'm at a loss as to why, when, I click "post video", and paste-in the URL of a youtube vid, only the link gets posted. Others here don't seem to have that problem. What am I missing?