Facing the rail is frontside, back to the rail is backside :) Easy way to remember!

Because your back is facing the rail.

Because you are turning towards your back

Because frontside is when you approach the rail with your butt and you could figger out the rest from there

This says back side but in the videos everyone is facing forwards ???

because when riding onto it the rail is behind you

That sounds retarded

When you are approaching the rail, it is facing your back.

Then is it a back side if you are riding the rail facing backwards or is it called Fakie boardslide??????

You are right you would be doing a fs 180 or 90 to land on the rail behind you. So this is mislabeled. Both board slide videos

Your back is facing the railing