Both these videos are fraudulent.
I don't know why he would do that (except maybe the income from 6.5 million views total).
Exactly how he obtains the voltages shown I do not know, but I could definitely fake a demonstration identical to what he shows here and achieve whatever voltages I wished.
In both cases he has constructed a single "cell".
The interdigitated conductors are connected in one of two groups.
The voltages shown appear to be generated by a single "cell".
He 'demonstrates' generating voltages of over 4V from a single cell. A silicon celltypically produces about 0.5 - 0.6V at 100,000 lux (full sunlight). If a cell that produced such high voltages from an immensely simple, low temperature 'cook' materials existed it would be widely used in a vast range of micropower devices. It doesn't.
His construction method is electrically symmetrical. There is no reason for one or other terminal to be positive or negative - even if the materials and methods used were capable of producing the voltage shown (which they are not).
His construction does not produce a 'doped' junction of P and N compounds. The role of a PN junction (which we have not got) in the PV process is outlined here Wikipedia: Theory of solar cells