Coincidentally, neither can I! I did some digging and found a fix. It would be nice if Forumotion actually FIXED it instead of providing workarounds, or at least admitted they changed something that broke this feature, but I suppose free is free.
SO, until something gets fixed, you have three options.
1. When copy/pasting the Youtube link, remove the '
S' from '
HTTPS://' to make it just '
HTTP://'. (according to the forum where I located this, this option will not always work, in which case use one of the next options)
2. You can also use the button right next to the youtube button in the editor view, the button that looks like a white square with a red '
F'. This embeds a flash element into your post (which the youtube embeds turn into anyway). You have to set the X-Y width and height of your flash embed, but apparently a good base size is 425x350... then paste the youtube link and it SHOULD just work.
3. Also, under a video on youtube itself, there's a button/link for sharing the video. Click the 'tab' for EMBED, and copy/paste the provided code into your post.
I have tried all three of these options since I discovered the problem, and so far they all work. I will let you know if this ever gets fixed back to normal. Sorry for the inconvenience, and hopefully this won't dissuade anyone from posting new videos!