USB fast charger using old PSU

[Plunger]

Being inspired by the video below I wanted to make a fast charger using an old PSU from a computer I was throwing out. Also 3,3V outage will come in handy.
But I can't get much out of the USB. I tried with my phone and compered to my wall socket it is much slower. I also connected my Raspberry Pi, and got an error doe to a shortage of power.
I have solders the data-pins and basically duplicated the video, why cant I get more power?
Also i am a plumber so the soldering I top tier for my trade

 

[AC Power]

While USB's will general the 5vdc required for peripheral devices, the current (milli-amps) available at them varies, even on a laptop or a full sized PC. So, your residential microprocessor (Raspberry Pi, Arduino, etc...) might draw in excess of the USB's capacity, especially if you've got your Pi operating several relays, small motors, and actuators. I've a feeling that's all you going to get from that small PSU.