Well everything with an LCD can be modded to a projector, and LED?, well any kind of power LED will do, or you can use 5mm (high power LED's) what matters here is getting a LED that is close to NEUTRAL White in it's emitting color, if you ever played around with LED's you will be familiar with the "normal" blueish color or the warm white, what you want is whats in between those, you can mix 50/50 but that's only good for general lightning, will look terrible used as a backlight for a projected LCD.

But get LED's that is in the 4000-5000K "color" range, and Power wise?, well the iPhone in the demo video has about 0.5W in LED backlight, so anything from 1-20W will make a very good projector when using LCD's that are less then 5" big, back when i made my DIY projector i used a 15" LCD Monitor, and that was when LED's where really expensive so i opted to use 2x 30W CFL in some headlamp reflectors i got from an old scraped Semi-Truck

And for the "tube" amp, yes it works but i would rather have some great AMP, and great SPEAKERS, to get some quality stereo sound.
Remember back when the first record players came, they used the same tube/horn amplification, back then not many power amplifiers have been made/invented + power was scares so it was better to have a wind up player.