Whatever floats your boat...
I was watching a Scott Murray vlog and decided to comment with an embed. But the little toolbar on top of the comment box (with the embed icon) was missing. I looked at several other videos and it was the same story. However, the comment boxes in the blog column--at least those I looked at--are intact.
I just started using Chrome, if that means anything. But I kinda think I've seen this issue before and there was a very simple fix.