Have you installed and enabled the MediaGarden.Videos module? That will give you the Video content type. Then from the Media Garden admin page when you "Import" your video file, it gets imported as an actual video content item (I'm not sure what would have
been created for you so far).
When this successfully happens, you'll see a link at the top of the page which will take you to view the item.
In the "Content" admin menu, there's a tab called "Content Types" - here you can edit all the existing content types to add or remove parts from them, so this is where you could add BodyPart to the Video content type (once you have it).
No need to apologise by the way; Media Garden works perhaps slightly differently to how other CMS's might handle media (this is because it's a whole pipeline that allows a lot of flexibility; e.g. did you realise than in 'query' you can paste in a URL to
a video file and it will also import that as the same Video content type?) So I realise it might be a bit confusing to start with, and also due to Orchard still being quite young some things don't work as well as they could (for instance in an ideal world
you'd just have to install FlowPlayer, and all the supporting modules would be installed automatically - the gallery doesn't support this yet unfortunately!)
Also, Media Garden will get a lot easier to use with the next couple of versions... right now it's a bit primitive in some ways!