There seems to be a big problem with all videos which have been posted on this forum.
(edited 18.45 - I've found a quick temporary fix to this problem which is to delete my cookies - see my posting of 18.43)
They don't work any more for me either on Firefox or Internet Explorer.
If I post a Youtube clip the usual way, I get this:
Which doesn't work, and that seems to the same for all the videos which have been posted. And clicking on the title won't take you to the Youtube page as it used to.
I've worked out that if in Youtube, you click on Share, then Embed, then select Use old embed code, copy the coding which appears above, come here, click on HTML icon at the far right end, paste the text there on a seprate line after all the lines already shown, you can then get it to work. But that's too complicated to be user friendly.