No problem. On the youtube page press 'share'. Then press get embed code. Copy that code and then go to the post you are creating on boxingscene. Press the globe icon and paste the link in the dialogue box.
Note that I'm not english so the translations of the wording on the youtube page might be somewhat faulty.
I am not able to get the embedcode myself when posting from my iPad BTW. I'm no computernerd.... So when I'm linking youtube vids, I post from a PC.
If my directions is not working for you, you can ask Tbear. He knows the english phrases.
PS: If you want to continue this conversation the way I do it, then press 'view conversation' under this post and then you should be able to post directly on my profile page. Alternatively you can just go to my profilepage and post a visitormessage.