Update youtube-feeds.js

I converted and standardized the syntactic style to that of node's core modules, including changing the indentation to spaces.
I removed redundant code and comments, adding comments where more documentation was needed.  Some code is verbose enough to document itself.
I added custom error constructors for some common error patterns, to reduce code redundancy.
I added strict checking (`===` and `!==`) where applicable.  Strict checking doesn't have the expensive job of coercing types to match, and thus is faster.
I added semicolons, which you seemed to have neglected.  Semicolons, while not technically required for execution, are necessary for valid code.
I lowered the default timeout to five seconds, because, while the industry standard is 30 seconds, I've found that 30 seconds is far too long to wait if the network is goofing up.  In almost all cases, you'll know within 5 seconds whether your request will complete.

Many of these changes are partially subjective.