The following videos are not perfect, and some of them are VERY old school, but they give a good frame of reference to all this talk of observation posts, concealment, and all that. Just take them for what they are and what is relevant to your situation. Discard the rest. You need to add modern technology to these basics, such as thermal and night vision.
The first one is a two part called ‘The Snipers’. It is a BritMil training video from the cold war. It is focused on snipers in a cold war-esque front line situation. However, it provides a good frame of reference (and plenty of laughs).
The Recce Patrol:
This one is on individual camouflage and concealment:
(Note: BritMil terminology speaks of cover from view/cover from fire, as opposed to cover and concealment).
How not to be seen:
More modern SAS OP Patrol Video:
Old school rules!