Hi bustermin,
I had a quick look at using the YouTube Capture app (i'm on iPhone 4 as well) and did a quick test and here's how to get the embed code. This is all assuming you're using your iPhone 4 for the whole process!
1. When you record your video using the YouTube Capture, in the app, you have to log into your YouTube account.
2. Once your video has been uploaded to your YouTube account, go to Safari browser and log into your YouTube account (note, from what i can see - or couldn't - you can't view your uploaded videos from your own channel within the YouTube Capture app. I guess that app is simply for recording and uploading videos only, not for managing your channel).
3. As you are using your iPhone, the browser website will most likely render its "mobile version". In this version, I also could not see the option to manage your videos/channel. In your options, scroll to the bottom and select view "full desktop version". NOTE: i didn't look at the official YouTube app, an option to view and manage your channel may be available there.
4. When the site is displaying the full desktop version, navigate your way to your channel and click on the video you just uploaded. Afterwards, look for the share link from which you can then select the embed code.
This process doesn't seem very intuitive so there may be another easier to do this. Also, i assume the forum allows you to paste in the embed html code and that it will render it.
Hope that helps!