I tested this on 110V and it delivered the same output voltages with load. (Just thought I'd mention that.) But this power supply has a few issues as shown in the video. It's a shame as otherwise it's quite a neat little device.
The 1A printed on the label may be the fuse rating. I'm guessing the power supply is rated for the full 2A at 5V continuously.
The hot optoisolator issue is probably because it's operating in its linear region and being part of a shunt regulated supply it is effectively a resistor. In hindsight it would have been interesting to bump the opto's LED current up to 6mA or more to see if it turned the transistor on harder and reduced the dissipation.
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