You no longer have to hit use old embed code on youtube if you're not the original poster. New videos that are uploaded on youtube no longer have the option of using the old embed code. However, using the normal embed code from youtube now works. Also let's be honest, I just wanted to share this knowledge with you to be able to share the video.
I did also want to make everyone aware about the youtube video stuff. That way if you go to share and don't see the old embed code you don't have to worry. The new embed code will work just fine as well.
Edit: This only works though if it is not the first post. The new code seems to not work in the OP. As I mentioned though, new videos on youtube don't always have the option of the old embed code now. If you are the OP and there is no old embed code to use, I would just make a post right below your OP. That is what I did below to share you the new code works.