daemon: (video) replace anonymous namespace by static keyword

Also minor code cleanup.

Rationale:
The C++ standard has un-deprecated the use of the static keyword.
But the superiority of anonymous namespaces is mainly for type 
declarations (including structures and classes).

For variables and functions, the static keyword is functionally
equivalent to using an anonymous namespace.

But there is a major drawback with the latter!
Name mangling for anonymous namespaces is such that it's awkward
to type/find a local symbol declared in them when using a debugger
such as gdb.

Refs #50143

Change-Id: I925af61d14db08fafa37bfbfeedde95feadd0948