I don't think they can copyright the way the page is laid out, only the images/artwork/logos and of course the CODE used. If the work is all yours and just happens to be laid out in a similar manner you shouldn't have any problems.
Copying the page source is not a good idea.
There are lots of websites that function like YouTube (such as Vimeo), the idea for a video uploading site isn't their own.
edit - Not sure why you'd bother though when the functionality is already there on so many other sites.