Suggestions For Betta Planted Tank

So I have a 15 gallon planted tank which houses just one betta fish. Basically, I would like a fully green and beautiful tank with my lovely blue betta swimming around.
I'd like some plant suggestions from you guys I use liquid fertiliser and just have a stock 15W bulb. I am interested in upgrading this because i'm aware that it is not very strong and i think the tanks lid looks ugly anyway. Does anyone know where I can buy a large bulb which just kind of rests on top of the tank like this person has: http/www.youtube.com/watch?v=k7RkfLlSG-Q&feature=related.
Does anyone know what the floating plant in fishkillernomore's betta tank video is? Here's a link: http/www.youtube.com/watch?v=LubYMbtL23E
Oh and last question, if I want the tank to be covered in green, can I just dump some java moss onto the tank floor let it grow?

Thank you for your time

Things like sagittaria and vallis will be good as they will spread through runners, allowing you to let it go as such. Or you could easy stem plants such as elodea or cabomba. You dont need to upgrade your lighting, its fine.

Sorry i cant help with the vids, will take too long on my phone