appears to be GHA, not bryopsis....broypsis has a fern, bushy look to it..from the video I do not see the fern like structures.
but I would check it against this website:
Green Algae
diagnosis is critical as removing GHA under water is OK, however you do NOT water to remove bryopsis underwater as the spores will release and multiple..this why bryopsis is so hard to eliminate from a tank..the only treatment that works is Kent Tech M..and lots of it....need to increase your Mg level to 1700 and leave for at least 4 wks..once it starts to die off (by turning a greyish color) it would be safe to siphon (do not pick out) of the tank.
the green algae on sand appears to be a type of cyano, but in green form...
So it is evident you have a high nutrient load in your tank...now the 64K question..where? you find that you cure your algae problem.
questions I would ask myself:
review the link I provided and carefully identify you do NOT have bryopsis
what the age of the tank?
what are you feeding the tank?
how much are you feeding daily?
how old are you lights?
how much flow is in the tank?