the first video:
that tank looks way over stocked, and the water is pretty cloudy, if you look 2minutes 25 seconds, it looks like theres a pacu in there with those red bellys..
those have to be cut lips, first those are not pygo's, not sure what specires they are but it looks like all there tails are in bad shape, one looks like it has two cloudy eyes, not to mention those are good size serras cramped in that tank..
not as aggravating as the first two, tank looks kind of small but nice piraya
*edit - looks like those p's in the second vid are sanchezies or macs.