On the first video you can see that the one swimming in glass still has a small yolk sac.update: today, i kept pups in the new tanks! But until today ( three days from giving birth) they don't eat! i'm worry!!!
They won't eat until the work sac is used up and absorbed into there body.
Think that if your keeping a pair of such expensive and demanding Rays you need to do a bit of research on them??