I can't tell you the water results until tomorrow I'm afraid because my dad deals with that but I will post them asap. We take the water test to the local pet shop who do the tests for us free. They use tablets in test tubes and then compare the color of the water to a color chart. We were told we live in a hard water area and that the tank is well cycled. We will have a trip there tomorrow and get the water tested.
I have another video here which is longer *sorry for my terrible leeds accent*:
www.twitvid.com/GIQXX
As for the fin nippers. The only other fish I have are the three baby oscars (could they be nipping him? I've never seen them do this they're more focused on each other and they're not aggressive as far as I know) two synodontis catfish who are really shy and two tiny parrot fish (could they be nipping him?) and two plecs.
Now i've read this I don't think it is white spot as he's always had the same marks and they've not increased so that's put my mind at rest! The minor body injury is probably because he tries to get into the caves you'll see on the video but obviously he's too big to fit.
My tanks 5ft by 2ft (plenty big enough but we can't have any more oscars now we're aware of that and if space became a problem we have other tanks) and has a Hagen Fluval Fx5 external and a dual filter internally. The hagen fx5 filters 1500 litres every hour which is twice the size of the tank. We do partial water changes every week without fail, standing the water and adding water conditioners. Sorry for the lack of knowledge, it's my dad who deals with this i just observe and learn!