How do I connect to Facebook and twitter widgets on the front page of metro?
The Facebook and Twitter widgets on the front oage of the Metro demo are just text widgets with images in them, you can edit those widgets in the "Top Row 1.4" position and wrap the images with links if that's what you're trying to do.
And how do I make the weather function work?
You will need to activate the S5 Weather plugin and place the widget wherever you want it to appear. The weather widget in the demo is custom HTML in a text widget in the Right Inset position.
The last question is how do I connect video to play in an I-frame on the front page?
You can look at the text widget in the S5 Tabshow - Tab 1 widget position to see how the video on the demo was done.