After looking at your video, it appears that the first fish is a male. The elongated second (black) dorsal spine kind of gives it a way. The second fish appears that it too may be a male, but I wouldn't bet my reputation on it. It does not have the elongated dorsal spine, but it appears to be about the same size as fish #1. Females also tend to be a bit smaller (about 2/3 the size of an adult male) As was already pointed out, the females have a pinkish belly and the males do not. The ventral fins on a mature male are also somewhat elongated.
I attached a picture of a pair of our German Blue Rams (GBRs) spawning. While not the best picture, you can clearly see the pink belly on the female on the left, while the male on the right is somewhat larger and has the elongated fins.
Hope this helps.