Hi,
Loop video it means that we use a 1-2 second video clip on loop, so you can play it for as long as you want. We usually put these automatically on loop, thats why some clips have red loop icon, some do not.
After it loops and 10/15 seconds later the continue button in the down right corner shows up. Continue means that you have already seen the whole clip and you can continue playing without missing anything new.
On most new animations we have loop on by default, because the animation is designed to be higher quality but shorter.
On the older animations many of them were made longer, and then I still wanted to let player watch it over and over again until he wants to move on.
Normally you never have to press the replay button, Either wait for animation to stop itself, or press continue when it shows up, when you feel like it.