It would help if you posted a schematic, rather than a video.

Were the transistors matched?
They're obviously not in thermal contact with one another.
In short, this is exactly what you should expect to happen. The transistors need have a similar h
FE and V
BE at a given current and be at the same temperature, in order for a current mirror to work properly. Adding emitter resistors may help and glue the two transistors together. The V
BE can be matched using the diode test function on a multemeter. Matchign the h
FE is more tricky, but not as critical as the V
BE.